The best tournament NLHE player is Phil Hellmuth. You can't argue with 11 bracelets, and he played bigger fields to win those. When Doyle won his first bracelet there were 21
The question was "best poker player" though. I assume that means you have to consider all the various poker games
like tournaments, ring games, Omaha, HORSE, Limit, NL, etc. That would exclude Hellmuth.
Doyle says that Chip Reese was the best. But now? Man... that's a tough one.
I'd have to go with Phil Ivey, but my knowledge of non-NLHE tournament games is pretty limited.