Legend, Angel, and Lich are exceptionally strong mechanically while Aeon is pretty weak, most of the others are somewhere in between.
Now that might have been true on release, but Aeon has been buffed a lot since then. Aeon has a pretty slow start indeed, you don't feel the surge of power with the start of Act 3, like some other paths do - although mainly
merged spellbook paths - angels and liches.
But by midgame they are already pretty solid and by end game they are definately some of the strongest mythic paths power-wise, able to make even bosses their bitches after effortlessly dispelling all of their buffs, preventing them from reviving and being immune to their attacks.