After experimenting with different builds and units, I've finally ended up with Quetz as my favourite.
My style is to go for a fast 2-TC. Then I try to push out in mid-heroic before it gets to late-game, using sacrifice in Great Temples. The units I like to play with are spears+archers early on, and then transition into Eagle Warriors + Jaguar Rider. I use the Smasher as a siege unit because I think the Stone Throwers are too expensive. I don't use traps. And I try to spam Warrior Priests and convert one as often as possible.
My default God-path is: Patecatl - Coyolxauhqui - Xolotl
I haven't used chicken devotion yet because I think the tech is too expensive and doesn't fit in my build. And I don't use Blodletting either because I don't want to kill my warrior priests. DESPITE THAT, I still think Quetz is the best one. Here are the reasons:
Calpullis bonus
Nothing significant, but he has the best early build with cheaper calpullis.
Tailwind
Basically helps you win battles. Since favour is easy to get early on, you can use it 2-3 times during the first 10-15 minutes. I think it is stronger than Blood Pact.
Healing Tree
Extremely flexible Godpower.
a) Get 800 food for fast heroic or early boost to 2TC-boom (get spears out)
b) Save villagers getting raided early on
c) Cast it in the middle of a fight to win. I haven’t compared it to restoration, but it is on that level, perhaps even better if you have many weak units.
Starfall
I think this is the strongest power-spike you can get with Aztec in heroic. I know how good the butterflies are, but that takes time to build up. With Starfall you can push right away and get 3 free myth units.
Military bonus
Best eagle warriors (+15 HP, +2 range)
Soul Guide spamming
Early mytic power-spike for Aztec