Rulk power level is all over the place. Hard to gauge him right now. He would give either a fight. Pulling the majority is what I am worried about. Anti Matter could possibly drop any of the other two though. With that said BM and Rulk wins.
BM looks to be the best on the field. Rulk has been meh the last couple of years, but still has quite the resume. OMAC has a solid track record against high tier, but actually lost to Frank. The Sword of Michael can be trouble assuming he matches Rulk instead of BM.