IMO the religious tree is the best overall, it pretty much keeps your country stable with conversion bonuses, state religion happiness, unintegrated culture happiness, and gives access to the religious/cultural conversion laws for monarchies. And it has the +2% levy size invention, the only one in the game.
Right Civic tree (especially with a hellenic culture accepted) also has a bunch of amazing inventions. Left Oratory tree is mandatory for grand theaters, early game AE control, and imperial challenge for blobbing after you've already taken the religious and civic inventions to keep your empire stable.
If you're playing tall the left Civic tree is the best since it'll make you a ton of money, and you can slack on religious ideas since you won't be expanding into wrong religion/culture group land that will be unhappy.
Honestly one of the best things about Imperator is how well balanced the tech trees are. Everything has a use depending on what you're doing. Except the naval tree, because naval tech being useless is a paradox tradition. And the right oratory tree is pretty useless too.