What pitchers to start in Fantasy Baseball?

I have 8 pitchers 6 to start and 2 to sit on the bench. My question is what 6 should I start this week Roy Halladay (1 start), Colby Lewis(2 starts), Brett Myers(2 starts),Jhoulys Chacin(2 starts), Anibal Sanchez (Probably 1 start), Jonathon Niese (Probably 1 start), Matt Garza ( 1 start), and Philip Humber ( 1 start). Garza, Halladay, and Humber all had good games this week and I would Like your input on the best 6 pitchers and info why would be nice. Thanks.