I don't think somebody like Zane should be considered best bodybuilder of all time simply because he has the physique that "normal" people relate to most.
If the question was what is the greatest male physique of all time then maybe guys like Zane could be near the top. But personally I believe a bodybuilder should carry more muscle mass than Zane while maintaining good conditioning, symmetry, balance etc. Doesn't need to be a mass monster either by the way.
I would say Lee Haney got the balance just right. A lot of mass but maintained a very symmetrical look with no bloated gut. Rounding out the top three would be Sir Ronnie Coleman (during his earlier years - around 1999) and as much as I hate to say it, Flex Wheeler (synthol aside, has there ever been a better responder to drugs than this guy)?