Personally? I'd much rather see Shawn Michaels vs. Kurt Angle (assuming Angle is in respectable physical condition).
HBK/Guerrero would be awesome as well.
As far as Guerrero is concerned though, I really hope that we can see him go up against Benoit. Guerrero vs. Benoit, title vs. title, winner take all. When you take their past into consideration, I think this match would have the ability to be the greatest of all-time (from a sports-entertainment and wrestling perspective).