GBA has the benefit of handling all games from the OG to the GBA games without being too bulky like the DS line. Plus GbA has some great re-editions of SNES games as well as Pokémon FireRed which is a nice revisit of the OG Pokemon (in my eyes). The backlight was awesome! The lack of headphones, not so much but it prepared me for the future (looking at you, Apple). The original GBA shape was much nicer though. I wish they had made a landscape console with backlight.
Luckily the GB(A) consoles are the easiest to mod nowadays, to add backlight, rechargeable battery, better audio... IMHO this is still the best way to enjoy GB/GBA games, instead of emulators which can be buggy/force me to stay on the computer (or worse, on my phone)