I'd rank them like this given your team:
Jones, Halladay, Sizemore, Thome, Pedro, Carlos Lee,
Sizemore will boost your AVG and help you out in steals a little in the OF, where you need an upgrade over Huff playin every day in such a small league. I might take him in the second round. Thome is always an injury risk in the second half of the season, and you don't need a 1b/util type, so his value is lower for you. Halladay and Pedro are up there just because you can always use pitching. Especially since Haren, Rogers and Lester are likely to fall off in the second half.