From a psychological perspective, I'd suggest it's better to have the name at the bottom, to avoid any internal bias of the user's name affecting how we read the Question/Answer, or worse yet - whether people upvote or downvote it. It's sort of like how well designed marking systems don't put students' names on the papers - because it can have a conscious or subconscious effect on how examiners judge their contributions.
Ideally I'd say contributions should stand on their own merit, and it's a shame when a user's identity causes us to elevate or downplay their contributions. And I think that happens to all of us.
On the other hand, I can think of a few occasions where I read a whole contribution and then get to the end and think "wow, this is better than I'd have expected from X".