Haven’t seen Rowan in action yet, but I’m going to guess the Statue of Liberty wins. She’s built of steel, and all she would have to do to defeat Stay Puft is get the torch going and roast him. Not to mention the crown looks like it could really hurt!
I imagine at one point in the fight, the SoL decks one of her opponents with her torch hand. Peter says “Nice punch Ray!” And Ray says “I didn’t do that.”