I think the problem is that as soon as people start posting their favourites people will start chipping in with "how can you say xxxxx is one of the greatest when xxxxxx hasn't been mentioned?"
The jazzers will start sneering at the rock/metal guys, the funk guys will start sneering at everyone else & that's how it will continue.
Unfortunately that's the problem when trying to compile lists of something that is completely subjective, and when everyone thinks that they've got better taste than everyone else.
For instance, I could write a list of 100s of what I would consider "great" bass players (i.e. I personally like what they do) & I can guarantee that Mick Karn won't be on there. Can't stand him, never could, but he's worshipped by large numbers of people on here.