I'm curious as to what everyone would say would be their ideal companion... If you want, list several who would fit the bill.
Now what I mean is what would be the most functional, developed, and creative companion for you in Fallout 4. Do you want a Super Mutant sniper (imagine it for a second) with a big heart who loves animals? Or do you prefer the ruthless killer who's aggression outweighs his since in that he might cause trouble with characters you might have a chance to resolve your situation peacefully (doubt we'd see that, but were talking theoretically.)
Me, I generally like to play as a big, heavily armored monster on my first playthrough who favors a peaceful resolution. So I'm saying I;m heavily armed, smart, and a great talker. So what do I want to compliment that?
I want a big, loyal, killer. I also prefer guns like the plasma rifle that do a crap ton of damage but it takes a second to get wound up. I have found myself using Veronica in New Vegas because she can crush heads and isn't such a big wide body like Lucy. This time around I could see my primary companion being Preston Garvey himself. Everything about his get up makes me like him. From his gun, his apparent need to protect the wreak, and of course him being the first real human we see our PC talking to.
My ideal would be a Brotherhood of Steel baddy with an even bigger gun or super sledge. The problem: We don't know how power armor functions exactly, so I'd say its much to early to say if we will see power armored companions.