Galactus: Possibly the most powerful being in the Marvel comics universe sort of Yahweh (maybe). Eater of worlds. Older than the universe itself. Some 30 feet tall, but it can vary.
Galactus’ death could bring about the destruction of the universe. Unicron wouldn’t care, he wishes to destroy the universe.
But, the “cincher” for me?
Galactus is a (admittedly giant, god-like) guy in a funny costume.
Unicron is a giant robot. ‘Nuff said.
So…anyone else feel like takin’ this one on?
And please, gentlemen…the contenders in this match are both highly advanced, highly powerful beings. They’re assuredly both VERY prepared, and have grown beyond the need for 1920s style death rays.