Not sure how I'm going to define childhood, but the only systems I had as a "child" were as follows:
SNES: 1995-1997, ages 10-12. Mint condition but got traded on my N64. Someone basically got a brand new SNES when they bought my lovely Super Mario All-Stars set.
N64: 1997-today, age 12 onwards. Still have this system, box and everything and is still part of my regular system setup. Has worked perfectly for 13 years straight. Joystick is still excellent, though that's because I barely used the standard grey one.
Atari Lynx: 1997-today, age 12 onwards. Was bought second-hand, no box or anything, but in as-new condition. Only had about 1 year of regular usage though, as new Lynx games dried up hella fast that year.
Game Boy Color: 1998-today, age 13 onwards. Xmas '98 gift, still has box and everything and has stayed in mostly minty condition ever since. Was in regular usage until 2001 when I got my GBA.
Going to stop there as I feel that 13 isn't really "childhood" anymore.