Which has more value, 56% Attack & Defense boost from a lvl 60 Zeus or 18.02% Critical Hit from lvl 60 AO?
Yes, the AO gives daily FP as well, but it also costs 62,000 additional FP (from lvl's 10-60). I have both buildings and plan to lvl both as high as I can... Most people will say AO, but have they looked at the numbers? Is an 18% chance of getting a Critical Hit worth an additional 62,000* FP?
* math wrong??
Zeus/CoA/CdM are pretty good up to L10, and then the wheels fall off in terms of combat ability. So, I'd say get those guys up to L10 in most situations, particularly since they are available much earlier.
After that, they move up .5% per level (averaged), as opposed to 3%.
AO goes up well after L10 by comparison, especially at higher levels. More importantly, those hits become extremely powerful at higher level when it's common. Most units you face will be the same age, especially those tough late L4 GE battles. If you're fighting units older than your age, it's normally not very difficult anyway.
Perhaps most importantly is those later ages where units max at "x" amount of damage. No amount of attack is going to change that, but AO does, and does so dramatically.
Plus, one FP per level never hurts, and that not only gets the FP, but helps with the FP quests.
So, up to L10, I like to focus on the attack buildings. After L10, I prefer AO. Also, certain ages, like CE, the AO completely changes the dynamics of battles if you can use units like mobile artillery.
One last thing, AO does help on defense, provided the attacker is using same age units. Since that is pretty likely, it can make a big difference in defending your city. None of the attack buildings have anything to do with defense.