In the main system of things, there 4 Main Handheld Systems from Nintendo. The Gameboy, Gameboy Advance. Nintendo DS and Nintendo 3DS.
Many of these systems came with upgrades like the Gameboy Colour, the GBA SP, the 3DS XL etc by the games can still be played on all the formats.
Which one of these set of consoles was your favorite?
The GBA SP was my baby. so Gameboy Advance gets my vote.