So, I did a points system with all the civs I've actually finished a game with so far scoring them in 5 areas: the Unique Units, Unique Infrastructure, Civ UA, Leader UA, and overall Synergy that these components can bring. Each area had a possible max of 2 points, with 2 representing the component is a good asset to the civ, 1 meaning it is decent, but inconsistently good (i.e. not a game changer, but something that still is useful), and 0 meaning useless, liability, or completely unnoticeable. So far, I came up with the following from what I've finished, game-wise.
America:
8 Points. 1 for the Units. They're good units, just limited in utility, especially because they're so late. 2 for the Film Studio - I think this building is incredibly undervalued and is an absolute winner for a culture victory. 2 for the Civ UA, as of GS - the wildcards are incredibly useful, and the extra favor is pretty strong of a boost. 2 for the Leader UA, because it's great for dominating your home continent all game, and their national parks are incredibly powerful. I only gave a 1 for synergy because the civ is trying to be a weird dom/culture/diplo hybrid now, but only the culture parts really fuse well enough.
Arabia: Haven't played yet.
Australia:
10 Points. Let's be real here. There's nothing bad about Australia. It's the only civ that can really make consistent use of its triggerable ability, the Digger is the only truly great modern unique unit, outback stations are OP, and their coastal bonuses put similar terrain bonuses to shame. And somehow, it all works gloriously well as a generalist civ that can do basically anything it wants.
Aztec: I haven't played Aztec yet.
Brazil: Haven't finished a game yet, but their bonuses were...underwhelming to say the least. Will score properly when I get the full experience.
Canada: I'm DREADING the attempt.
China:
7 Points. Okay, so there's wonderful culture and science synergy in the whole civ. Their Civ UA is incredibly useful, as is the Leader UA. Extra builders, more wonders, powerful eurekas/inspirations are all wonderful! 2 points each in the abilities/synergy areas. Makes a really good civ in those areas. The Great Wall is kind of cool actually, not amazing, but does give a bit of synergy with the civ itself so I gave that 1 point. The Crouching Tiger...is kind of useless? I don't think I really got any utility out of it. It's just one of those units that is "there". Plus, I'll take 2 range crossbow any day over a 1 range crouching tiger. 0 points.
Cree:
8 Points. 2 points each for the Synergy, Leader UA, and the Mekewap. All of those together create a wonderful generalist/builder civilization that can pick and choose what they want to go for. Of all the strange victory combinaitons I got, I pulled a renaissance/industrial religious victory off with them. The Okitchitaw is a good unit, but not amazing, so I only gave it 1 point. I also like the Civ UA, but it's also not overwhelmingly grand, so just one point there. I love my traders claiming tiles though
Dutch:
6 Points. Why do we play the Dutch? Polders. And Grote Rivieren. Polders can be difficult to place sometimes, but they are a strong improvement when you get that great placement. Also, it's nice that they can now be built on submerged tiles! Grote Rivieren is a pretty powerful ability as well - you can create some great adjacency bonuses where other civs don't get any. 1 Point for the De Zeven Provincien - it's strong, but there are better UUs. I did get some good utility out of it though. 1 point for Synergy - there's some good generalist synergy here, but nothing to go crazy over. No points for Wilhelmina's bonus. It's barely noticeable in the grand scheme of things. I used it when I was desperate to keep a city's loyalty, but it's rare that you can't find a better way to boost loyalty. There are far better loyalty bonuses.
Egypt:
6 Points. 2 Points for Iteru, because that itself was always quite useful. 1 point for everything else. The Maryannu is strong, but I don't find it amazing. The Sphinx is decent, but again, there are better culture/faith improvements/strategies. The Leader UA is nice, but again...not anywhere near the top of the game. There's some good culture game synergy here, but Egypt is kind of all over the place as well.
English/Eleanor:
6 Points. Don't get me wrong. I love playing Eleanor - her ability takes some set up, but when it gets going, it's too much fun. She gets 2 points for court of love. 2 Points as well for the RNDY. I think, personally, it is an underrated UI as it does a good job making coastal cities viable, and gets lots of gold. This also helps with the 1 point of synergy, since I think the RNDY's gold is excellentl, plus since there are still continents with long land connections, it can help hold flipped cities. Not the MOST synergy, but there are some good strats to be found hidden in this design, IMO. 1 point for the Civ UA - WOTW isn't something to go crazy over, but I found it marginally useful. It's certainly not TERRIBLE, but the underlying systems really need a buff to make this power as strong as they probably intended. 0 points for the Sea Dog. Another case of a unit that is just "there". Why do we have this? Jeez.
English/Victoria: I didn't finish my R/F game with them, so I won't score them until I play GS with her. But GOD was I underwhelmed. I'm not really looking forward to another game.
French/Catherine:
7 Points. Great culture game synergy - cheaper mid game wonders are always amazing. Some really good backdoor domination synergy too. Overall, I really like Catherine's France for all of her abilities. 2 Points each for the abilities and the synergy. 1 Point for the Garde Imperiale. It's a GREAT unit, limited by its availability and the fact that it is hard built. Wish it just replaced the Musketman. 0 Points for the Chateau. I built a couple, and I think I placed other things over most of them that were more useful. Underwhelming improvement, to say the least.
French/Eleanor: Gonna have to see what I can pull off here.
Georgia: I tried to do a Georgia game before GS came out...I'll try again but I won't be happy about it.
Germans:
8 Points. The Hansa is why I play this civ. The extra district in every city is awesome. There's great builder/generalist synergy here, and particularly great production possibilities for a science victory. Definitely one of my best games. Only 1 Point for the Leader UA: i like the extra military policy (extra policies are useful), but I don't care for the CS conquering bonus. Only 1 point for the U-Boat. That might be a tad generous, but I think they're a decent unit overall. Better than the Sea Dog at least...
Greek/Gorgo:
9 Points. The Hoplite is a tad underwhelming, but good for early game culture grabs with the rest of Gorgo's abilities. Just one point there. Two points for everything else. All the other stuff about Gorgo just works super well. The Acropolis is amazing. Culture from kills is great. Great synergy. Extra wildcard is really nice.
Greek/Pericles: Haven't tried him yet, but almost positive if I gave Gorgo a 9, he's around there too.
Hungarian: In progress. I'm pretty sure he's getting a high score here.
Incan:
9 Points. Only 1 for Mit'a because it's more nice flavor than anything else and makes a normally totally useless tile kind of nice. Otherwise, the Waraq'aq is great, Qhapaq Nan is awesome, Terrace farm and synergy are all wonderful. Had a blast with this one - one of my new favorites.
Indian/Chandragupta: Have yet to try.
Indian/Gandhi: Played around a bit with them in vanilla but need to try the current version.
Indonesian: Played around a bit after they came out, but kind of difficult to set up right. Will try again.
Japanese: Never finished a game with them yet; need to try again.
Khmer:
7 Points. There is some honestly great food and faith synergy for this civ. I love Grand Barays - I think it is much better than people give it credit for. Also, gimme my suicide missionaries! Prasats are a great upgrade for the temple. Domrey gets 1 point - nice unit, kind of out of place in the grand scheme of the whole civ. And as much as I like the food/faith synergy of the civ...Monasteries of the King is abysmal. It's definitely the weakest part of the civ. Plays in a bit with the rest of the civ, but isn't super useful.
Kongolese: Haven't tried yet.
Koreans:
8 Points. The Hwacha is a good defensive unit, but it's drawbacks keep it from being great. Also, Hwarang only gets 1 because it's kind of hit or miss sometimes. You can get some really good governors with lots of science/culture, but only in a few cities for most of the game. Not always easy to take advantage of. I think that Three Kingdoms is highly useful in tandem with the Seowon, and there is great synergy in the civ for a good science game (also culture). 2 points in each of those categories.
Macedonian:
10 Points. I hate admitting this, but Macedon is easily one of the best civs in the game. I think the Basilikoi Pades is the "weakest" part, but it's still REALLY good because it encourages your science growth and military expansion so well. Their units are pretty dang good, and those abilities are just OP.
Mali: I have yet to play but they're next on my list.
Maori: I have yet to play, but they are after Mali.
Mapuche: Haven't tried, but I'm curious since I like fighting them (they can bring somewhat of a challenge to conquer/war against).
Mongolian:
10 Points. There is nothing bad about Mongolia. Nothing. And it all works together better than just about any other civ in the game. They get bonuses to the best classes of combat units, as well as that fantastic doubling of diplo visibility combat bonus. This actually ended up being my best game, pleasantly surprising me. And because they can take what they need so well, they can do just about anything, too.
Norwegian: I tried playing them awhile back before any of the "buffs", but was not impressed. Will need to try again.
Nubian:
10 Points. I've loved few civs as much as this one. A builder civ that is just as dangerous in war as any warmonger civ. Extra boosts from mines. Cheap ranged units. Pitati Archers. Nubian Pyramids take some tricks but you can get some great yields from them. Cheap districts. Yes please.
Ottomans: Have yet to try.
Persians: Played around with them for a bit but didn't get a good game really going.
Phoenicians:
9 Points. I give the Bireme 1 point. It's not the greatest thing ever, but the trader protection is awesome early game. Otherwise, I had a lot of fun with Dido. Cothons are magical. Their settler spam and ability to claim any (coastal) territory and resources they want are awesome. Extra trade routes? Great. I'm a fan of cheaper government plaza stuff too. Fantastically done.
Polish: Haven't got a good game going with them yet.
Romans: Played around a bit once - need to do a full game, but I liked what I saw.
Russians:
9 Points. Grand Embassy isn't terribly grand, but it really helps early/mid game when focusing on religion so you don't stay too far behind. Otherwise, Russia is brilliantly designed. Great religion/culture games, good domination (or even just defensive) potential thanks to the Cossack. Lavras are fantastic.
Scottish:
7 Points. I love Scotland. But Bannockburn is just non-existent because of difficult requirements (0 points). It's a non-factor. Highlanders are okay as defensive units, but not anything screaming to be built (1 point). There is a GREAT science game with Scotland. Also, your cities are permanently overflowing with happiness (you work a bit for it, but golf courses can go a long way). MORE great Engineers and Scientists? Absolutely!
Scythians: I hear they're amazing - played around a bit, but need to give a serious game.
Spanish:
6 Points. I might be being generous here. But the conquistador is worth 2 points to me. Does it require micro/setup? Yes. But these bad boys were game changers in my wars. Incredibly powerful. Otherwise, everything else is just inconsistent. Mission is okay, but really moreso on foreign continents which can be trickier to set up. Abilities are fine, nothing to scream over (I like trade route bonuses though). Some imperfect synergy for religion and domination.
Sumerians:
8 Points (maybe 9). Lots of people list Sumeria as God-Tier. Which I understand. They're great. But the Leader Ability is kinda crap? Maybe it's not as bad as I think, but I didn't really find it super useful so i didn't give it any points...I could see giving it a 1 though with the new pillage buffs. But everything else IS God-Tier. The War Cart alone is enough to make me afraid. Ziggurats are a great improvement. I think that Epic Quest is awesome - extra goody huts where no one else can get them AND cheap levied units (which can get otherwise expensive). Great science/culture/dom synergy.
Swedish -
9 Points. The Carolean is good, but a tad underwhelming. Everything else synergizes perfectly for diplomatic or culture victories. OAM is OP. Nobel Prize is OP. Queen's Bibliotheque is lovely. Automatic theming is awesome. Loved my Kristina game.
Zulu - Haven't tried but i really don't like being their neighbors!
i know this is all totally subjective (and I'll update as I go), but that's how I've been doing it in my nifty chart.