More often than not I prefer no face cam. I don't know, I just usually don't like it being there. I feel like it takes away from what I actually want to see (gameplay). I get distracted easily, so having the person in the corner of the video making faces and whatnot messes with me. Lately Dashie has been using face cam for a lot of his gaming videos and I'm not really a fan of that.
In special cases though, I do enjoy face cam. Mainly scary gameplays and when it's a group of people playing a game. I've been watching through JD's Mario 3D World gameplay lately and it's hysterical watching him and Dave and all of them fighting and blaming each other and stuff. In that case, the face cam is awesome.