Who wins this fight?
Game Genie
Gameshark
Pro Action
Who wins this fight?
My Gaming Collection (Now at Google Drive!)
Game Genie by far, by its cultural significance and universal brand recognization alone.
Game Genie. Though the Pro Action Replay (Gameshark in the US in early years) could let you find your own cheats, only the Game Genie could let you HACK the ROMs!
The only reason I didn't like Game Genie as much as the other two is because it limited you to only a small number of codes at a time so you had to mix and match wisely and try different ones at different times.
Pro Action Replay was the hacker's choice. The ability to play imports was arguably more important than the cheats.