My general read of this thread is Dragonlords has better PC material, Theros has better DM material. And if you just want content to run your own Ancient Greek-esque campaign, Dragonlords might be a better bet.
Overall, I'm happy with Theros. Oath of Heroism is a little meh, but I really like College of Eloquence Bard. The new races, rebalancing the Triton are all pretty solid. I'm really happy with the piety system and the Mythic monsters (and bestiary in general). Supernatural Gifts are okay, but a little thin, I'd have liked a few more options, or more guidance on adding more.