I'm going to have to say
Clemente Luna is the best player I've ever had on a team. His career is starting to wind down, but he's been a monster for the time I've had him.
Although:
Troy Galey looks to surpass him in a few years. Too bad I haven't had him from the beginning.
If you want pitching players:
Josh Beckett Has had a fabulous career for me, but:
Rich Oberg and
Larry Bartlett look to be monsters of the staff.
And since I'm whoring links, here's my fantastic closer:
Jairo Frau.
Yeah, I'm a powerhouse in the league.