I loved the Game Gear. It truly blew my mind when I learned as an adult that it was basically a Sega Master System made portable. Made me imagine what could have been if the Game Boy had been a portable NES.
Favorites: Sonic Spinball, Castle of Illusion, Taz Mania, Chuck Rock, Mortal Kombat.
Mostly for the convenience of having all of the games on one platform?