A companion with some character! Not some random DB murderer with no back story who just follows you around like a puppy.
This. Hopefully the companion characters actually have a personality, a backstory and maybe even some quests attached to them. I'm cool with the idea of everyone not having dialogue in exchange for more people, but if the people you actually do meet end up being lifeless - and your responses to those people end up being lifeless - I'm going to be a little disappointed. Maybe not overall, but in that aspect definitely.