The black and white nature of some of these posts is crazy.  Each guy does things.  Each guy is poor at some things.
As of now, I think Prey is more serviceable especially since we don't need him to score.  Hopefully if he is here next year, he gives something on the offense end.
I think that Vince is a work in progress.  He is a presence, but often seems a out our of sync and sorts. 
Each guy I think warrants limited situational minutes.  If I had to pick one for extended play this year, if needed, it would be Prey.  But I would not write Vince off for the future.