Pretty weak list. Thomas is probably the best bet, but he's always a question mark. I would pick him up and see how it goes, if he gets hot ride him out for the season.
Without knowing what your team lacks (speed, power, etc), I'll say Hart, Thomas, then Bradley.
Hart will help you in multiple categories and has a lot of potential. He's also good to plug in the OF in case one of your 3 or 4 OF's go down (higher chance than the other positions).