Its been fun going through this thread. Now whenever anyone tries to do a list like this there is so much to take into account.
The biggest question to ask is what makes one wrestler better than the other? Seems simple, but its a loaded question. Is Hogan better than Bret because he made his companies more money than Hogan? Or is Bret better than Hogan because of his in ring ability? For a question like this the criteria really needs to be specified.
What I like to do (and have tried to do in the past) is take into account all the factors that go into making a wrestler great. In the same way one might look at a basketball players scoring, rebounding, assisting, stealing, and blocking stats to come up with the best basketball player, I try to do something similar with wrestling. IMO, it begins with being a main eventer. To consider a wrestler to be the greatest they would have had to had a run in the main event. From their I would consider such factors as:
in ring ability
marketability
promo work
charisma
ability to play face/heel
Now I have no idea how each should be weighted, so I never fully dove into rankings, but if I ever got an idea how each attribute should be weighted it would be worth a go.