Definitely Michael Stich.
He had an outstanding backhand that he could hit any type of shot with very well (topspin, slice, drop shot, passing shot etc). In the last 20-25 years the only player I've seen with a one handed backhand return as good as his has been his compatriot Becker.
His clearly had an excellent serve with one of the smoothest service motions I've ever seen and was a strong volleyer. He also had superb athleticism and could move very well on all surfaces. His forehand could be shaky at times but he worked hard to improve it and it was excellent during his 1996 RG final run.
The backhand overhead is the hardest shot in tennis in my opinion, but for him it was a speciality.
He was very comfortable serve-volleying or staying at the baseline. Courier and Newcombe labelled him as the most technically complete player of his generation which I agree with. Sampras said he was the opponent he feared facing the most. Even his ultimate nemesis Agassi praised his talent, ability and versatility in his autobiography.
He was certainly more well rounded and had better results across all surfaces than any of those other players. Goran never reached a slam final outside Wimbledon, never reached the semis at either the Australian Open or Roland Garros and never won a big title on clay. Krajicek never reached a slam final outside Wimbledon, never reached the semis at the US Open and didn't win a super 9 title on clay (although his one career clay title at Barcelona was still a pretty big one). Cash didn't really do much of note on clay.
Stich reached slam finals on grass, hard and clay, reached the semis or better at all 4 slams and had some good tournament wins on all surfaces.
Last edited by Gizo; 10-12-2012 at 10:59 PM.