PSP, although it sold well I feel like people gave the system way too much shit. Played that more than my DS.

But I guess if I had to pick a true underdog, the Dreamcast for sure. Died way too soon, had an amazing 2 years.

The Dreamcast it was ahead of its time it had online play before it was common. Plus the VMU's where pretty good also. On top of all that it had one of the best launch games in North America with SoulCalibur.

Definitely the original Xbox. The hardware (CPU, GPU, RAM, built in hard drive, built in ethernet port) was significantly more advanced than PS2 and Gamecube, so it typically had the best looking version of cross platform games. It also had a lot interesting PC games ported to it. Not to mention some great Sega exclusives and the original Halo. Oh yeah, and Xbox Live, which at the time was a pretty groundbreaking service to have on a console.

People tend to not think much of this system since it had a pretty short life and overall didn't have a lot of really memorable games to call its own. And of course the system and its original controller were kind of ugly.

Gamecube and Dreamcast

I'm going to go with the Gamecube for now. I wouldn't be surprised if my answer changed to the Wii U by the end of the generation though.

It wasn't really HD. It was just upscaling the image. Like what Metal Gear Sold 4 does on the PS3. Or all the 900p games. Which is funny. The PS2 did the same thing. But everyone now goes ape shit, if it isn't real 1920x1080. I'm saying PS Vita or Gamecube. The orignal XBOX did fine. I don't know why it's there. Saturn. Sega's fault it messed up. Master System, it's fine too. It's just forgotten about in the Sega history line sometimes. Vita. Sony didn't screw up. It was just something that wasn't needed. And failed for those reasons. Gamecube becase of PS2 and Xbox making it become ignored. And appearences. It was still actually good. 

Easily the WiiU. it's not the most powerful, but it's got some great innovation, the controllers (Pro and Tablet) are awesome, the games so far have been outstanding (Smash Brothers, Mario Maker, Mario Kart, Bayonetta, Mario 3D World, the Wind Waker remake, NSMBU, Donkey Kong Country Tropical Freeze, etc) and the Virtual Console is the best it's ever been.

I don't play it as much as my PS4, but I play it a LOT more than my Xbone.

A few of my friends have the Wii U. I just can't get into the gamepad. I have really tried it and given it a chance. It'd be awesome to have as an option but I like to play all my games with a smaller controller. 

The new smash kicks ass though. 

Gamers forget about the wii... really a fantastic console that dominated the market from 2006-2010. So many exceptionally great games (galaxy) and even more hidden gems (marumasa, zack & wiki).

Atari Lynx.