I too voted for 2600 and NES. I have fond memories of playing PacMan, Megamania, Space Invaders and Space Cavern on the 2600. Alot of that time was on a 6" B&W TV that I had the antenna rigged up to the switch box because there was no cable jack.
My XBOXs get more time playing roms from those two systems (more convenient than the real thing) than they do playing "real" XBOX games.