GBA was my childhood. It was the first gaming system (other than PC) that I was introduced to.
Some of my favorites:
Banjo & Kazooie: Grunty's Revenge
All Pokemon games
Donkey Kong Country
Super Mario World: Super Mario Advance 2
Yoshi's Island: Super Mario Advance 3
Mario Pinball Land
Kirby and the Amazing Mirror
Kirby Nightmare in Dream Land
Mario Kart Super Circuit (First game I got)
These games made up so much of my childhood it's not even funny.
What's even better is I still have all my GBA games AND my GBA.
...with classics such as Kirby and the Amazing Mirror (arguably the best Kirby game of all time, next to Super Star)...
This. So much this. Amazing Mirror was my absolute favorite game in the world. After I played it I was completely OBSESSED with Kirby. Anyone who knew me back in 3rd-4th grade and especially the one summer camp I went to would say all I ever talked about was Kirby.
Sadly I lost the cartridge a long time ago and was dying to play it for a really long time but then they
released it in the E-Shop. I bought it the day it went in the store. Now I play it all the time on Wii U.