Well, Im no Superman fan, but the fact that he is able to control the position of his body, (flying, hovering, etc), anywhere in 3d space, and is actually able to use that to move planet-sized objects, this ability, whatever u want to call it, would/should give him and edge over guys like Thor and Hulk.
No matter how strong they are, even if they r stronger than Supes, in truth, all they have on thier side, to give them leverage, is thier weight.
So, for this contest, i think u would need somebody with similar powers, or controlling gravity, or controlling thier own mass, etc.
Let's say, as long as Supes does not use his strength to injure limbs, Graviton could possibly beat him.
Or Juggernaut could probably do it, using his "directional momentum unstoppable" power, thing. He should, theoretically, keep his body from moving out of position, while, unstopably moving his arms.