America - I feel like this one could do with some shifts, certainly, though the +1 sight is a nice, solid, understandable bonus. I kinda want something a little more punchy and unique, like, "Gain three times the free tenets for early Ideology adoption" would be pleasant and maybe represent how they practically adopted Freedom in the late Renaissance era. It would encourage you to industrialize and/or modernize fast, which would also fit pleasantly. Of course, there's plenty of other options, like boosts from railroads, or as others have suggested, bonuses from liberating cities. Minutemen could maybe be buffed, and...egh, I don't know what to do about the B52.
Arabia - Already changed, needs little else. Camel Archer has always been kickass, Bazaar has always been super broken, UA is now not super crazy and more sensible but unique regardless.
Aztecs - Needs no change, IMO. I really like the UA because of how simply and elegantly it encompasses the civ, both the obvious of how sacrifice through battle was an important part of their culture, and simulating the "flower wars" fought not for land, but for ceremonial purposes. It's a fun thing that encourages warmongering without conquest, making an enemy of the world so they can send billions of units to you while you strategically kill as many as possible. Jaguars are still really great, and pumping them out early on nets you crazy awesome infantry, and Floating Gardens is powerful as always.
China - PLEASE PLEASE change this, I just...REALLY don't like it. Powerful? Sure. Boring? VERY. It's the most bland warmongering ability, and does China no justice whatsoever. A major center of civilization and one of the most powerful nations in the world today, and we get...more great generals...yay? I want something that represents their historical technological innovation. A simple, powerful thing I thought of was this: Technologies require only one prerequisite to research. It makes beelining desirable techs an effective strategy, and offers a lot of flexibility and powerful options, especially in espionage. The Paper Maker should make resource diversity in trade routes provide science for both parties involved, as China was the endpoint in the Silk Road and along it, gave the world many innovations while learning from them as well. Chu-Ko-Nu is fine.
Egypt - UA is good, simple, effective, encourages very cultural play and is pretty satisfying. War Chariot...mmh, it's good, but...I kinda don't like how it doesn't require Horses, because it just...makes little sense. It's using horses. Those are right there in the icon. At the very least, something like only using half of a horse resource would be good, and maybe a little extra promotion, like, bonus versus fortified units would be cool. Burial tomb is interesting enough, though giving it a GW slot like it does in the Africa scenario would be cool.
England - Part of me wants a decent bit of change, but hmmm, I don't know. Additional range to naval trade routes would be cool. Longbow...eh, it's super good, I know, but I kinda want a UB or UI in its place, because I like those over secondary UUs. I have no idea what it'd be, though. Ship of the Line is boring and could use spicing up. At the very least a Discipline-like bonus to adjacent naval units, whether ranged or melee, would encourage tight fleet battles that crush people when used in packs, as opposed to the bland combat bonus it has now.
France - Everything is fine, UA definitely makes you scramble to become civilized because if you miss out on those fancy wonders, well, tough, you gotta take them. Musketeer is a little boring, I do not like straight combat bonus units. I kinda want something silly like generating Tourism for each unit killed, but that'd be a bit out there. Chateau is super good and crazy awesome when Hotels come into play, so yay.
Germany - Topic of much much discussion here. Simple idea I poked in places: "Hanseatic League: Trade routes with City-States give +25% Gold and Science. Engineers give +1 Culture and Happiness." or, if you want to get really crazy, "Forge of Empires: May choose Tenets of every Ideology, regardless of which one is picked." Landsknecht, out the door. I don't like it at all. Give a Workshop or Factory replacement with three Engineer slots that provide double GE points. Panzer, give additional flanking bonuses, and another boost if that tile has had an Air Sweep. Effective blitzkrieging, super powerful for how late it comes. Put the barb recruitment in Honor or something.
Greece - Still pretty simple and powerful. But either the Companion Cavalry or Hoplite should go in favor of a UB cause that's how I roll. If Hoplite stays, give it an additional bonus on Defense or so. If the Cavalry stays, give it...I don't know, an additional Great Work for capturing a city?
India - Ugh. Does not do India justice, once more. Religious or Cultural bonuses are a must. Someone suggested the ability to found a second religion, which I found kinda cool, and would work neatly. War Elephant...hmmm, don't know what to do with it. Give the Feared Elephant bonus? Mughal Fort...is tolerable, I guess, notable for being the only building which to my knowledge gives a flat Tourism bonus, so that's something.
Iroquois - Fine as it is. I like the touch of Caravans having the Forest bonus applied to them, gives nice options to early trade route options. Mohawk Warrior is cool and powerful, Longhouse gets some crazy production. All is well.
Japan - Definitely kind of...smeh. I don't know what to give it, but Bushido is kinda blah, though effective for naval battles, and apparently it doesn't work exactly as written? Ugggggh. Unhappiness from Ideology pressure halved (or removed outright) would be nifty, Great People costing 50% less Faith would work nicely, etc. etc. Samurai could, I dunno, provide a Great Work while garrisoned? Zero, replace with a Dojo or Torii or something like that. A shrine that provides XP or a WAM specialist would be cool.
Ottomans - Conflicting. They're effective, but...kinda boring, especially with Privateers available, and it doesn't do well to convey the rich Turkish culture and all that. At a loss for what to do, though. The Sipahi and Janissary are both cool and I don't know which one I'd want to go. Sipahis are cool mini-Conquistadors that are effective at scouting and whatnot, Janissaries are super iconic and all. I guess the Sipahi would go, and be replaced with the Turkish Bath or so.
Persia - I don't know. I'd kinda want it to change, but it seems fine as-is. Immortals are effective, Satrap Court...okay, kind of comes way too late, and should replace the Market instead, but is otherwise simple and effective.
Rome - Easy to understand, extremely powerful. Legion should pass on the road/fort construction on upgrade. Ballista should poof and be replaced by a UB, though what that is I have no idea.
Russia - Haven't played them enough to get them well, but while they look a little boring, they also seem pretty powerful. Double strategics is no joke, and you're really encouraged to go military without direct bonuses, which I generally like, or you can opt instead to trade your riches and swim in gold. Nice production bonuses too, so yay. Cossack should...get some nicer things, kinda bleh, Krepost is...alright, I guess. It's a civ that could do with subtle tweaks, but not any I can think of off-hand.
Siam - Still effective as ever, though I wonder if that should also apply to Mercantile and Militaristic CSs too, though it might be a little broken. Stampy is cool I guess, haven't used it that much, Wat is cool though a little bland.
Songhai - Arguably the civ that got the most indirect buffs without changes to itself. Leaner initial gold means you can skimp on the trade routes and still stay in the black, and you have good encouragement to conquer. MPM is cool, gives you nice culture and no maintenance, always nice. I rather like the Mandelaku, as it makes an effective conquering horde when backed up effectively. It's good and doesn't need much change IMO.
And there you have it, my comprehensive opinions on what vanilla civs need change. DLC ones are all fine in my opinion, though Denmark could use a UB in place of the ski infantry, and Spain a UB in place of the Tercio (which should be renamed into Pike and Shot and be the Renaissance anti-mounted unit while the Lancer is in the cavalry line), and maybe the Khan could be made into part of the UA and give...some UB/I. Same with Korea and the Turtle Ship, I guess.
. You trade Copper for Citrus and Gold for Gems. This gives you +12
