And here's the rest. Fortunately, due to the fairly evident power of these civs, it shouldn't take much explaining.
List
20-15
14-11
7-10
Great
These civs possess overwhelming powers that could arguably be considered broken. Will generally perform very well regardless of situation as their bonuses will apply much more often than not. Most feature at least one passive ability that allows you to ignore parts of the game.
6. Rome
Rome has traditionally been a player friendly choice, and you don't get much more friendly than a free monument. Early culture is very hard to come by as mere survival is a concern. One can be very busy with expanding and building troops, so monuments often fall by the wayside. Often times you have to rely on inspirations to get to a proper government in time. Rome will always get there reliably, and the more cities they build early on, the better it gets. It does take some action early on though. On higher difficulties, this bonus is not as strong as often times you will capture AI cities that already built a monument among other things but still decent for Political Philosophy. This also reduces the luck factor as some inspirations can be harder to get.
The legion is a stronger swordsman and requires no iron, which is always nice since your warriors can upgrade to them; it also makes their higher production cost mostly irrelevant. They also have the odd ability to construct forts and considering anything that improves tiles in this game goes away once you use up charges, this is one of the cases where it may come in handy.
All Roads Leading to Rome is a decent tactical advantage if you trade internally early on, making sure your empire is roaded and easy to move around. Also good for new conquests as well.
The Bath is okay. Aqueducts are kinda lousy as you sacrifice a river spot to gain 2 housing which you may not even be able to use due to amenity problems. The Bath provides an extra amenity and 4 housing (more so if you lack fresh water) so that really helps cities grow upwards. Still nothing that exciting in most games, but it's nice to have, especially if you capture a city with an aqueduct or something.
Overall: Stable civic progression
Preferred Strategies Expansive and trade
5. Greece (Gorgo)
Essentially, the same as her Athenian counterpart, Greece's acropolis allowing for envoy spam, bias towards hills, and free wildcard slot makes Greece enjoy easier starts. Gorgo's bonus of culture per kill is a bit more reliable than Pericles because you just have to kill stuff. And you can kill barbarians too, which means even if there was no war possible, you could still take advantage of it. It also may encourage you to actually want barbarians to show up and not clear camps that fast. Later on, it starts to trickle and unless you're fighting very strong and advanced opponents,. it may not make that big of a diffrence anymore. But with the spare culture, Gorgo is much like Trajan in the sense you'll get your government faster
Overall: Very straightforward and strong abilities
Preferred Strategies: Barb hunting and finding excuses to fight
4. Russia
A lot of times one can't just place the best long term city early game as it will take too long to yield benefit. This becomes more and more true as the game progresses. A lot of times it is better to settle near mines and resources so the city won't be useless for the next 30 turns until it can finally grow into your dream spot or you spend tons of money buying tiles. Russia, though, just takes all the land, with their Mother Russia ability allowing them the best of both worlds. This also presents a strange way of dealing with barbs, as you can literally settle away their camps if the tile the camp is on becomes part of your city. And yes, you do get the gold for clearing it.
But a lot of land is useless though. While Russia's ability doesn't make tundra great without additional help, they make it so you can make the best use out of normally unusable land. Basically those crappy frontier cities will pick up a little more faith and production from tundra.
The Lavra makes Russia a top choice for actually going for a religion. It's cheaper, gives more prophet points than usual, and also does more than religous things. It also gives you points for culture people and thus Russia can get ahead in the culture game while chasing religion-- as a result these are never lost investments even if the religion route goes bad. Even some blank lavras can be pretty good. Of course, you'll need a space to put great works; do remember your palace can hold 1. You also get extra tiles for recruiting GPs which is nice, though nothing that spectacular. But with Holy Sites, anything is a good thing.
Grand Embassy means you can get extra science or culture for trading with a more advanced civilization. This is an excellent mechanic that scales well with difficulty as it's unlikely you'll be ahead in both all the time. Especially applies during early game where you're more likely in an expansive phase and have less infrastructure which allows you to balance science and culture better.
The Cossack is good, being a slightly better cav, but especially so when defending. It also can move after attacking and this is incredible although it does come sorta late.
Russia's just really good at making the best out of land, so get lots of it!
Overall: A well rounded, and adaptable civilization that is bound to steal plenty of land.
Preferred Strategies: Culture-religous hybrid, and Papal Primacy if possible.
3. Aztec
With escalating district costs as the game goes along, developing new cities can take too long to even bother with. Unless you're Aztec in which case you can make cities come online with a few turns given some preparation.. Regardless of era, you will make any district you need with 5 builder charges. As a result you can fine tune your empire to suit whatever victory condition you want, and turn it around on a dime, either just by building or capturing more cities. The most outrageous ability would be to 1 turn a spaceport using 5 builders left with 1 charge left surrounding the spaceport location. By grabbing the great people needed for Space Race, this pretty much means you can use almost any crappy location to win space.
This alone would be decent enough but it hardly ends here. The Eagle Warrior is not only much stronger than a warrior and available from the start but it can capture enemy soldiers (not barbs, that would be ridicilous) and turn them into builders. And Aztec due to the above district ability always welcomes more builders. This ridiculously snowballs upon conquest as you've probably captured more slaves and want to immediately develop your newfound cities. With these things, you don't even have to be successful to take anything-- just kidnap some builders which ironically isn't considered warmongering. Oh, and Eagle Warriors cost no maintenance, meaning they don't have to worry about conscription too much, and can do stuff like take Classical Republic easily.
But to add even more icing, there's the luxury bonuses. Aztec luxuries go 2 cities further, meaning you can make even more ciites that are bigger without hassle and their combat strength increases per improved unique luxury. So now your stronger troops can either help you capture even more stuff, or just kidnap workers, or use them to defend your ever growing empire.
Their unique building is sorta bad, mainly because entertainment complexes in general are bad. The little smattering of faith won't help much, and certainly not worth a district slot until zoos appear.
Oh, and the luxury combat bonus also applies to religious civs, so if they get ahold of a religion, they can become a threat there. Not to mention it'd be easier for them to even build Holy Sites. As a result, they literally can do anything and are arguably god tier in many cases.
Overall Powerful bonuses for any occasion with perfect synergy.
Preferred Strategies: Science, Domination
God Tier
While low tier civs suffer from being left out of the game's mechanics, these civs don't just adhere to the mechanics, they basically define them by being overbearingly good at them. Opportunity cost is simply not a thing and in general picking these civs is like lowering the difficulty.
2. Sumeria
I dunno what they were smoking when they thought of warcarts. They're stronger chariots that aren't weak to spears, aka no counterplay, and are available at the start. Sure it can't steal builders like the Eagle Warrior, but it might as well, with its mobility. It will thrash through any nearby opposition and unlike the Eagle Warrior even if they get caught in a bad spot can simply run away. They also cost no maintenance and upgrade to knights, meaning Cleopatra is probably in a corner crying somewhere while everyone else is admiring Gilgamesh's massive... beard.
But even if Gilgamesh can't find anyone nearby to instakill (and with war carts, nearby is kinda far), he gets more rewards and potential for clearing camps, which is no problem for war carts either. Aggressively exploring the map looking for camps in your spare time is not a bad idea. Basically he gets to enjoy goody huts for the entire game.
Adventures with Enkidu, the ally based bonuses, aren't too good right now since it can be hard to get an ally, though being able to come to war on behalf of an ally has some interesting diplomatic effects.
The Ziggurat is also pretty solid, as it effectively allows you to plant science everywhere, and even culture if you put it on a river. It's very helpful early game though not so important later on but it does give flight based tourism so there's that.
And that's it. And more than enough.
Overall: Monster warmonger with diplomatic choices
Preferred Strategies Conquest and alliances
1. Scythia
What could possibly be worse than Gilgamesh's complete military dominance early game? Well, what about Scythia's dominance for the rest but still being really strong at the start? Scythia's troops smell blood and get a bonus vs any injured unit, so basically the way to avoid it is to not get injured. Good luck with that, espeically with the Scythia light cav and horse archers producing double. Although the plain archer rush works just as well and is deadlier than usual.
So they have a combat bonus. I know, let's give them another one. Scythian units heal for 30% health once they make a kill, so in even fights, they're going to hold the advantage and snowball. Oh, and if an almost dead barb passes by, too bad, Scythia can heal on that too. Enemy CS 2 eras behind? Good enough. This also gives them a huge edge in theological combat too. Basically if you get beaten by Scythia not only will you be beaten down but their units will be healed and now stronger so you have done nothing but provide a minor roadbump. How's that for demoralizing?
The 2x light cavlary bonus is also pretty over the top as well, as some one thought it'd be a good idea for them to be biased towards horses. Saka Horse Archers though, aren't too exciting and they cost a bit of mainetance too, so don't go that crazy.
The Kurgan is alright in case you wanted to generate faith early game, as pastures shouldn't be an issue but it has a little utility.
In all fairness though, Scythia is pretty (but not completely) war reliant so on isolated starts, far spawn starts (but then again with horses far may not be that far), Gilgamesh and Monty may surprass Tomyris. But if there's any poor soul near her that isn't Gilgamesh or Monty, well....
Overall: Proficient in combat throughout the entire game
Preferred Strategies: Conquest