I would rate them:
1. Eaton (pitcher's park, 2nd year off TJ surgery, good offense behind him)
2. Weaver (highest risk of this list, but could be huge, pitcher's park and great bullpen backing him up. Could rebound to his Tigers' form)
3. Williams (he has been terrible in spring training and might suffer the sophomore jinx and is at risk of being sent to AAA. Probably the best in keeper leagues though)
4. Zambrano (He pitches in the AL East, which means facing Toronto, Yankees, Red Sox and Baltimore often, and these are probably the 4 best offenses in the AL. Also, TB has a weak bullpen and fairly weak lineup behind him)
As for Wakefield, I probably like him about even or just below Eaton. Even though he is a knuckleballer, he is a fairly consistent pitcher, and he also racks up a good amount of Ks. Wakefield is a lock to win 15 games with that offense behind him as well. Wakefield is the safer choice, Eaton is the upside choice.