Let's look at Aztecs:
UA: Gets you off to a great start, and gives you decent rewards for winning wars.
UU: Very powerful from the start, but falls off and is very player-favored. The AI can't keep them alive as well as the player or harass a neighbor as hard, which leads to them being even worse for the AI.
I think the best use is to surround an enemy's capital with them and make them a non-starter. This is a powerful tactic against that person and somewhere between hard and impossible to stop. The AI doesn't do this, which hurts them a lot.
However when other players are involved this tends to be less of an advantage than it could be. Other people can settle the land you freed up, not just you. Other people can win early wars and have abilities that extend into the game further.
UB: Went from a very powerful building that helped keep Aztec alive into the game, now fairly bad. It got a bit of culture in the last patch, but it no longer shores up their kit.
Next let's look at the balance changes that have affected the Aztecs:
Authority being balanced: As an early warmonger when authority overperformed Aztecs were a primary beneficiary.
UB/Watermill nerf: Mentioned in the description but this was really, really impactful. They had an absurdly powerful version of an OP building, and now they have a stronger version of a weakish building.
War nerfs: The AI getting better at war, benefits being curtailed a bit and reactiveness to warmongering have made a warmonger's life a bit harder.
Religion nerfs: This is the big one. The guaranteed ability to found with basically any pantheon was a HUGE benefit. It was said that to win you needed to found or usurp a religion. That's been nerfed time and time again. More people can found. The beliefs benefit you less. The non-founders benefit from more stuff.
Now let's look some other similar other warmongers:
Japan:
UA: Very comparable in power. Less faith, but you'll probably still be able to found. Golden-ages vs GAWM is a bit of a toss-up.
UU: This is always going to be the hardest comparison. The Jaguar warriors are very situational and become worse as the map gets larger, depending on who you're next to and depending on if you're a player or AI. However I think Samurai come at a very good time where you're ready to incorporate large swaths of land, so I'm going to call it a toss-up again.
UB: So much better. The massive amounts of yields you get. The fact that they're of the best types. The combat bonuses you get. Dojos are seriously some great UBs. This is what makes Japan stand a head taller than Aztecs imo.
France:
UA: blows Aztec's out of the water. The rewards for winning war are so much better than the Aztecs it's not even funny, AND they get a combat bonus. (If not the most potent one.)
UU probably rates lower. It's always apples to oranges, but The lightning warfare nerf hurts.
UI: Really hard to rate. Both give more yields, but that's all the Floating gardens do. Chateau makes your land far more defensible, but requires a bit more effort.
Overall you have a similar but inverse problem. You're very dependent on your start. If you get a weak neighbor you can bully you've got a great package, but if you don't you're in a bad spot. Aztecs are more consistent, but France is far more potent. I would rate France quite a bit higher because I would rather inconsistently dominate than consistently underperform.
Greece:
UA: A tiny bit weaker than Aztecs. They can get a combat bonus as the game goes on that can become very significant, but is also disruptable. If your enemy kills your city state allies he can de-power you. That said the recovery speed combos really well with the next part of his kit.
UU: Great. Fantastic. Amazing. The power and consistncey of these units is really great. Honestly just the ability to demand tribute can get you off to a really strong start, and you can also take a few cities at least with these. A very powerful unit that I really like.
UB: This is what blows Aztecs out of the water. Culture on EVERY KILL! The incredible power of this ability is mind-numbing. This scales harder than anything anyone else can offer. The ability to get hundreds of culture per unit killed late game turns even wars into victories and winning wars into massive swings that can propel you to the head of the pack.
So Aztec's problems are that it gets a pretty good start, but lacks the power to finish off games. Here's my suggestion:
Floating Gardens add: City gains +10%
/
during Golden Ages. Remove the 2
.
UA: Land Melee units gain a promotion with "During a golden age unit gains +10%
CS, +15% damage versus wounded units and converts 25% of damage to cities to
culture." (
@Gazebo if this is too much new code, could you please something similar that is possible.)
This gives the Aztecs a bit more reach and synergy with their own kit. This really gets them to chain wars, and works well with the history behind flower wars. It also means the time they're strongest right now (super early) they don't get any stronger, because golden ages are not going to occur naturally or while you're ready to really leverage them.
I almost worry about stepping on Persia's toes, but your wartime bonuses during golden ages are weaker and I think you're different enough to be happy with. Look at Portugal and Ottomans for example.
I would probably remove the ability for the bonus in forests to carry over on upgrade from Jaguars to balance these buffs, because that would also make this change more AI-friendly. (Which is always a goal, because you're going to play against any given civ more than with it assuming you don't spam one civ.)
I'm interested in other player's thoughts, but this is my opinion on a civ that got nerfed while the landscape simultaneously changed around it in a method that hurt it quite a bit.