Well, it depends on how they get paired up really. If Surfer gets paired up against Superman and Quasar gets paired up with one of the energy manipulators (energy siphon ftw), could be a HUGE swing for the GMH side. However, Ronan is the weak link here and could get taken out early, making it a swing for the JLA's side. Thing is, the Worldmind would prolly be scan the combatants and inform the GMH to pair intelligently.
But the JLA team is solid as heck with no weakpoints other than Superman's weakness exploit problem.
Also, using the Boom Tube argument, Nova has actually USED his startgates offensively before. Unless Orion has had instances where he's used the Boom Tubes offensively, that type of argument actually helps the GMH side.
However, I will have to give this to the JLA. 5.5/10. Just no weak links and IF Superman -doesn't- get taken out early (via Surfer weakness exploit) it's almost sure that Ronan will be taken down by just about anyone in the JLA grp...