These are my rbs Ray Rice, Frank Gore, Pierre Thomas and Jahvid Best who should i start i need 3?

Start Gore, Thomas and Best. My RBs are good, too. They are Frank Gore, Arian Foster, LeSean McCoy and Jahvid Best. I would trade one for a stud WR but I have Andre Johnson, Miles Austin and DeSean Jackson. A better TE? I have Antonio Gates? A stud QB? I have Philip Rivers. 10-team league. I'm beasting!