The Handheld Revolution · 1989–present
Game Boy Color / Game Boy Advance
GBC / GBA
Sought After?
GBA especially — it's a gateway into the SNES-quality library in portable form, and special edition shells (Pokémon-branded, Zelda-branded) sell for a premium.
Downsides
GBA's original screen was unlit, a puzzling step back that Nintendo corrected only with the later GBA SP and Micro revisions.
Why It Faded
Both were naturally succeeded by the dual-screen Nintendo DS.
Trivia
The Game Boy Advance could play original Game Boy and Game Boy Color cartridges, giving it functional access to well over 2,000 total games at launch.