Who should I start this Sunday?

In our league we have a flex position so I can start either 3 RBs and 2 WRs or 3 WRs and 2 RBs. I'm not sure who I should start and would like some advice. Here are my RBs: Earnest Graham, Warrick Dunn, Derrick Ward, and Chris Johnson. Here are my WRs: Hines Ward, Plaxico Burress, Donald Driver, Anthony Gonzalez and Greg Camarillo. Thanks for your suggestions.