this is tough b/c as you stated, it's still really early and things can change by the end of the year. BUT, if the year ended now, I'd go:
1. Sizemore - no brainer (unless this injury keeps him out for more than a year...)
2a. Youk - 3B is a really shallow position & if he's eligible there still, he's got a lot of value
2b. BJ - he's still young and has speed. We know he's got some pop in the bat (saw it in the playoffs) and if he can find that, it'd be tough to not hold onto.
3. Bills - STUD pitcher (If Hamels is back to last night's stuff, then I'd rank him above Bills)