Fantasy football question?

ok so i have Ben Roethlisberger and Mark Sanchez. i dont know who i should start, Roethlisberger is playing against the Raiders Defense and Sanchez is playing against Houston's Defense. Also if you think i should start Roethlisberger do you think i should start Mike Wallace too? thanks just lemme know what you think and if you can say why you think that, thatd be cool.