I enjoy almost all of my GBA games

Final Fantasy 1&2 Dawn of Souls
Final Fantasy IV Advance
Final Fantasy Tactics Advance
Golden Sun
Golden Sun: The Lost Age
Sword of Mana
Kingdom Hearts: Chain of Memories
Tales of Phantasia
Castlevania: Harmony of Dissonance
Castlevania: Aria of Sorrow
Legend of Zelda
Legend of Zelda: A Link to the Past

The upcoming Final Fantasy V Advance and Final Fantasy VI Advance will be something to look forward to