I just finished reading Blue Marvels respect thread, and he seemed to be a notch below Superman, a slight one. I'd say that he'd punch J'onn's ticket, but I have no idea what his psi resistance is, or if he has any at all. Physically I seem him dominating J'onn. His Anti-matter powers could also kill J'onn in a phased state.
For now though, I say J'onn wins due to lack of feats on Blue Marvels resume.