RK Thor wins and it’s not close. After he pierced the veil, he was no longer capable of being harmed physically, and he became omniscient. This is seen while no selling Mangogs punches. Not even 1% of the punches power registered, and was seen as completely ineffective against RK Thor. Meanwhile a regular classic Thor was able to physically rip open the armor of a Celestial with his bare hands.
This is a non battle.