well, if anyone could match supermans strength, its juggernaut. plus id say hes more indestructable. he lacks the speed and ranged attacks, but in a cube like this it wouldnt be a huge issue. it comes down to juggernaut being physically indestructable, and healing from any damage he takes almost instantly. his powers also have mystical origins, something superman is weak against. the only time ive seen him really damaged is when his flesh was town from him (mystically, not by any physical force) and he continued as a crimson skeleton, the only result seemed to be he was alot angrier as the skeleton.
other than that the onslaught thing i dont count, it broke alot of cannon and contradicted itself a bit. superman probably has more impressive feats, but the amount of issues superman is in vs the amount the juggernaut is in makes it pretty pointless. he hasnt been given the oppertunities to show what he can do in the way superman has. as cool as he is, i cant see superman doing any lasting physical damage, if he can do any at all. juggernaut doesnt fatigue, so if the fight rages for days hed be as pumped and have the energy he did when the fight started. juggernaut wins.