Hmmm, 'great' could be decided in a lot of ways. I assume they'll be going down the popularity route, moreso than the 'Who's had the most great matches?' road.
Also, is it just WWE? Will they be including the non-WWE work of some wrestlers? I know little about, say, Harley Race but I know he accomplished a hell of a lot more in NWA than WWE...

I think they'll put Austin at #1, and probably Hogan at #2. Hell, didn't Vince say that Austin was the greatest WWE superstar ever before he got inducted into the HOF?