I think the most underrated console was Virtual Boy. It's the only Nintendo system I don't own, but I wanted it so bad. Sure, it's not perfect virtual reality, but I thought it was pretty cool from the store demos I played. And its failure caused Nintendo to severely punish Gunpei Yokoi (who also invented Game and Watch, the whole concept of a control pad as opposed to a joystick, and, of course Game Boy) who was killed by a car a few years later.
Very sad.