Jamie Gold, obv...
Serious answer - I think that as soon as Hellmuth wins a non NLHE tourney - possibly even the big HORSE tourney - the arguments against him being "best ever" (whatever that means) will start to be personal, not factual.
Until then, he's the best ever NLHE WSOP player. (so far)
As for the best ever all-around? You have to consider Scotty - winner of the ME and the big HORSE tourney - that's pretty impressive. (drunken douchebag interview notwithstanding)
Doyle should be considered, but the small fields when he won most of his bracelets takes a bit 'away' from consideration.
It's a tough question in general - everybody's definition of greatest ever is different.
OT