Civilization/Leader Reviews:
CivName (Player Rating/AI Rating)
Out of 5
America(3/1): The scouting bonus is OK for human players as knowledge is power and it also helps early on finding the ruins and avoiding barbarians. The buying tiles is an average ability. The minutemen are controversial since they can't use roads and in some situations can actually be worse than the standard musketmen. I find them to be worth the disadvantage. B17 is great if you can last long enough. The AI is absolutely terrible with America and doesn't benefit much from either bonus. Every time I've seen America they are crushed just about by the time they get minutemen.
Arabia(4/5): I have personally never had a problem with oil before, but even still it does mean that you can trade away the extra oil for goodies. The real winner here is that trade route bonus. It's nice for the big expansive civs, but it really, really helps the AI. Every game I've seen with Arabia in it results in Arabia quickly becoming one of the top two civs. The trade route bonus starts to get out of control and I've seen AI Arabians with 30,000+ gold. The camel archer can also be very hard to finish off and are thus a better than average UU.
Askia(3/2): Askia really locks you into being a warmonger, but they are decent enough at it. They need to pillage constantly to use their ability. Their unique building gives extra culture, which makes it one of the few buildings that rounds out a civilization more than directly helps their abilities. In this case though, their unique ability is so focused that I don't believe their unique building is useful enough to them. Their unique unit is great and it's pretty much the closest you are going to get to being able to play as Atilla the Hun. Despite the fact that this side should benefit well from the AI bonuses their extreme aggression tends to make them too many enemies and other AI's gang up on them very early.
Aztec(1/2): Their unique ability to gain culture on kills seems to not give enough culture for how often units are actually killed. Furthermore, their unique unit is often obsolete before most players will even be in conflict with another civ. To make matters worse, even with start location preferences on, there isn't even a lot of jungle around the Aztecs. Even on hot maps with high water, the amount of jungle in the game is minuscule and I can rarely ever benefit from the jungle bonus. The water mill may be the worst building in the game. Not only can it not be built in all cities, but even in places it can be built it often isn't better than the normal water mill since the bonus only applies to LAKES. Even on the map "Lakes", with hot temperature and high rainfaill these guys are only average.
Babylon(4/4): Their ability, like every science focused civ in almost every 4X game, is extremely good. Their unique building is OK and helps them science whore, as does their early unique unit. Basically, every game you science rush initially, using your early game advantages to out tech neighbors. Once you are an era ahead you have a lot more freedom on strategy.
China(4/4): A solid civ all around even without needing to be a warmonger from the get go. Their unique ability does favor frequent war, but it also helps the more peaceful china get the first few great generals that could save your ass. Their crossbowman is amazing unless you are underteched, in which case it will do less total damage per turn than a normal crossbowman. However, with the paper maker (which is one of the best unique buildings) you shouldn't be falling behind in tech.
Egypt(3/3): Good unique ability with a mediocre unique unit. Their unique building is so good that it actually needed a downside, making it the only building I know of that can benefit enemies.
England(4/2): A great civ on any map with significant water. The speed bonus easily lets you have colonies on the opposite ends of the world and still defend them. Longbowman are one of the top unique units in the entire game. The extra range means you can have an army entirely devoid of siege weapons since longbowman can outrange cities, saving you the research and really letting you exploit this UU. Their other unique unit, the ship-of-the-line is very powerful, cheap, fast and comes at a great time. Considering how bad ironclads tend to be you can easily use this unit until you get destroyers. AI hates water so no surprise at that rating.
France (4/5): Their culture bonus early on is amazing and allows for fast expands better than almost anyone else. The two back to back great unique units means that if you don't take down France early they will warmonger their way to the top 3 every single game.
Germany(4/2): These guys are very luck dependent. If you don't end up killing a few barbarian camps early on you are at a massive disadvantage. Though most players will probably play these guys very warlike they don't necessarily need to be at war since their ability is dependent on barbarians and their unique units are still useful to deter enemies, and save production that could be better spent elsewehere.Their unique units are great and if you can survive from ancient age to actually get panzers you are probably going to demolish everyone else. The AI will unfortunately spam their unique pikeman a bit too much, to the point where you can easily build an army of crossbow/swordsman counters.
Greece(5/5): An absolute powerhouse of a civ if you start in the ancient era. I've only seen AI greece lose once (and it was to another one of the frequent top 3's). Their ability is generally useful. Like Rome, both of their unique units are in the same era, but since only one even needs a resource they are much more useful. Greece tends to explode outward with these two units, giving them a commanding lead which is rarely reversed.
India(2/1): India's ability is a bit better than it seems, but it really forces you into certain strategies. The larger the map is, the worse their ability and since most of the maps are already a bit big they are at somewhat of a disadvantage. Their walls are ok, but ideally you want to stop invaders at the border and not 1 tile from your cities. A smart player will just pillage everything in India. Their unique unit is short lived and serves only to make sure that India isn't quickly wiped out with an early rush. The AI consistently fails with this Civ because of it's love for expansion and because of how AI bonuses work.
Iroquois(3/3): An average civ all around. As with the Aztecs, even though the game tries to make your start position friendly for your civ I've found many time I don't actually have that much forest. Also, you won't get much use out of it early on as your cultural borders will be small. The mohawk warriors are average since forests aren't always easy to come by. I kind of think they need map conditions with high rainfall just to remain competitive. Their unique building is well designed though and combines very well with their unique ability.
Japan(4/3): A great ability, a great unit (samurai), and another average unit (zero). The ability works best for the AI as they are more likely to fight when injured than a player probably is. The only downside is if you are facing a a ranged heavy army and you aren't quick enough to change to using more cavalry units. The zero, while good on paper, is not that useful in singleplayer for either the AI or you as the AI doesn't build almost any air units.
Ottomans:(2/2): The ability to take over barbarian naval units makes this ability even harder to pull off than Germany's, with less payoff, and also making it entirely useless on maps without water or with little access to it. You can always be guaranteed to find barbarian encampments, but not always barbarian galleys. Their two units are at least average though.
Persia(4/3): If you play to exploit persia's ability with extended golden ages this is a great civ. However, maximizing golden age timing and frequency is a more advanced civ skill so many players won't benefit as much as they should. Their unique building is good enough to be built in just about every city. Immortals are average.
Rome:(3/3): I personally love their unique ability. It's really their unique units that are an issue. The legion is great and it's ability to build forts and roads makes them one of my favorites. However, they require iron and their other unique unit, of the same time period also requires iron. This means that if you are somehow unlucky enough to not be near iron it can spell a quick game over. Unfortunately, even if you have iron both of these units get obsoleted rather quickly.
Russia:(3/4): Siberian Riches is average, as I rarely ever run out of resources and since this is typically a large expansive empire you should have plenty. The unique unit is fine as is the Krepost and they fit Russia's playstyle. For some reason, the AI's bonuses cause Russia's natural expansiveness to balloon out even more and Russia ends up being one of the top 3 every game.
Siam:(4/3): Somewhat luck based, but overall very good. I say luck based because it really depends a lot on which city states are near you, what type they are, and how many. It also matters which players are near you and how aggressive they are to you and your city-states. The unique ability is great, but there's always the chance that you will invest in a city-state that get's destroyed unexpectedly. Also, since most players will run this civ less expansive than most, maritime city-states don't benefit you as much as if you were a larger civ, so you don't want to have a lot of maritime city-states most of the time. The wat is a great building and should be built everywhere. Their unique unit is kind of like the minutemen in that it has a terrible disadvantage of lowered speed, which means it isn't for killing trebuchets and such. Considering how rarely I see mounted units used, especially against Siam, a defensive civ, the bonus their elephants get doesn't help very much.
Certain civs tend to lock you into a certain strategy. You can try to do other strategies, but you'll just end up wasting your abilities.
War: Askia, Japan, Aztec, China (Oddly enough, Germany, and Greece which can look extremely warlike, aren't mostly dependent on going to war with other players and city-states.)
Expansion: Russia, France, Arabia, Rome
Culture/Science: Siam, India
Most others are fairly balanced.