While I hope it's not the only thing Tavs have going for them, I think the tadpole skill tree is a decent unique thing. The other origins can get new power still but they could be fixed based on character, while Tavs get the branching choices.
Companions have the exact same illithid power layout as the player character...
here in this gif posted by PlayStation you can see Gale's brain layout for illithid upgrades and he's not the player character because you can also see the party has a dragonborn in it.
