I think the best god would be Hera. Happiness is a very effective skill to use. Wedding is also nice. If you were to utilize them two correctly, you could have a constant flow of resources. Well, at least for early game.
After early game, say around 1,350 points (building levels according to that point count), I would choose Athena for the Patroness skill which grants 5 land units. It's a little pricey with 60 favor each, but it's worth it in comparison to the resource requirements. I also like Heroic Power.
Zeus is a nice god as well. I personally enjoy Divine Sign for 1 chariot per use. For 50 favor? That's pretty cool. Chariots are boss. Lightning bolt is also good. I'm not sure what some real use would be, but I guess it'll be good in support of friends/alliance/pact members. Favorable wind seems effective as well. Increase naval force? I would think that would be good in conquering. Then Zeus' rage would be great defensively. Though it cost 300 favor, it's almost impractical.
Haven't paid much attention to the other two and I hardly use many spells for each god so, just some food for thought.