My favorite player is Daniel Negreanu, followed by Phil Hellmuth.
They're very different players, but I love both their styles, and they're usually very entertaining at the table.
My least favorite players are Antonio Esfandiari, followed by Humberto Brenes.
I'm not sure why exactly I hate Esfandiari, but for some reason I just can't stand the guy.
And Humberto - he's just plain annoying. Watching the National Heads Up Championship I felt like knocking him on the head repeatedly with a live shark while shouting "Who's the chark now? Who's the chark now?"