Gameboy was already a multi-millionaire franchise even before pokemon, not to mention that Gunpei Yokoi invented first nintendo console the Game&Watch and inveted the d-pad, only later he created the gameboy. Yokoi was almost as important for nintendo in the past as Miyamoto was. Satoshi Tajiri on the other hand has permitted Gameboy to expand it's life cycle from 1998 to 2001.
I whould choose Gumpei for sure.