well, i'm not oly, but . . .
it IS very close. the difference in strength would be negligible. supes is stronger than cm imo (oly will say something like -- they've always been shown as equals, bio says equal, . . .) but there is quite a convoluted history between supes and cm that explains quite well why they have always been depicted as equals. i'd also give a slight edge in strength to supes over orion, but as i said, the differences among the 3 would be negligible.
since strength alone wouldn't decide the outcome imo, and i'd also place durability at about equal, it would come down their respective skill in battle (a very definite advantage to orion in that area) their extra abilities (an edge again to orion in this area -- a motherbox to counter solomon's wisdom, the astro-force, a direct and IMMENSELY powerful aspect of the source itself, orion's healing via motherbox and astro-force) and their attitudes. orion was built with a bloodthirsty always-ready-to-kill attitude -- "KILLING IS WHAT I DO!" -- direct quote from orion.
these extra abilities would be enough to give orion the majority i think, though cm could win a couple. be interesting to see how a few lightning strikes would affect orion. still orion in the majority after very good battles.