First person all the time--best way to be immersed for me is by seeing through my own eyes, as it were.
Though I must say, I'm rather surprised at how pleased I am with the kill camera stuff. When I first heard about it, I was frustrated that my beloved immersion would be interrupted by having my eyeballs burst out of my skull in order to better witness a spectacular kill--but that's not the case.
Like folks say, it's nice to see your character, and having the camera pull back every now and then to show your virtual representation pummeling a bandit, or crushing a wolf's skull, or climbing atop a dragon in order to introduce your axe to its neck are moments that let you see you digital abilities in a more appreciative light I suppose.