Umm... what does it matter Hulk's size?
I've seen him start out a fight with him thinking Betty was dead, and he even had the image in his head... and he was still getttng his ass kicked by Abom...
Galactus wins.
You don't pimp slap Surfer out, manhandle Tyrant, stalemate IN-BETWEENER, KO Beta Ray with one closing slap, only to lose to Hulk.
Galactus wins 10/10.