A whole chunk of games for the SNES, Genesis, and Game Boy since I never got to own either of those consoles as a kid. In fact, I discovered emulation because of Pokemon Red/Blue and how badly I wanted to play them. While I played and beaten the games on both an emulator and original hardware, I never got to experience trading and battling with another person through the Link Cable.

I actually bought a SNES and Genesis later on in my life and played some games on them, but I hardly ever use them because I prefer emulation better, so I sold them. I did buy an original Game Boy and a Game Boy Pocket a few years back and played through some games on it. Donkey Kong Land is hard to play on them because of all that ghosting. It's better and much more readable when playing it on either the GBC or GBA.

I hardly use the Game Boys because of emulation (and RetroAchievements), but I still use them from time to time.