Keeping it simply by using only Olympia winners, the best bodybuilder would probably be Sergio.
The rest would be a competition between Heath, Zane, Scott and Cutler since they really didn't have any poor bodyparts as such. The big guys like Arnold, Haney, Yates and Ronnie had poor hamstrings, biceps, biceps, calves respectively. If they were reduced to the quality of those bodyparts, I don't see how they could hope to defeat Sergio or even Heath or Zane. Samir only had weak hamstrings so he falls into Arnold's camp with that one. Dickerson also lacked biceps so he would destroyed and Dexter has no calves.
Of course, some moron is going laugh at comparing Larry Scott with Jay Cutler but I'm referring to their physiques at the time they competed. Scott may not have had the best structure but he didn't really have a weak bodypart in the way that Yates had weak biceps, for example.