I own a Wii U, Vita and Gamecube. Wow, I suck at buying consoles.

Nintendo 64 and Atari Lynx, the latter is the only handheld console I ever owned and the N64 is easily among my favorite systems of all time.

Gamecube and Dreamcast were something big but they were both killed by the excessive hype over the PS2, especially gamecube that had impressive games but never got the praise that it deserved.
We have to admit that Sony knew how to target the mass with its hardwares since the PS1.
Also, the fact that Sony went for CD-roms and DVD-roms at that time played in their favour not only in acquiring more licences, but also in selling hardwares all over the planet, where an easy hackable one was THE HUGE argument to buy it.

Can see why the Lynx could leave salty image of handhelds.  You never got Gameboy?  Tetris was God back in the 80s.  Then there was a thing called the DS.  Still waiting for switch I can put in my pocket.

I own a Wii U and a Vita. My lowest selling system is my PSP Go, although that technically doesn't count as it's part of the PSP family: It flopped hard but I loved mine to bits.

Mine is the Atari Jaguar. Only sold around 250k worldwide which is tiny. In the UK (where I live) it isn't that hard to get though. Prices aren't super crazy either.

Sega Saturn. And I'm sad Sega ended like that.

WiiU - I loved it so much!

Same for me. Even in the Kickstarter-exclusive brown edition and with my Username etched into it to boot.

Although we did own an Inerton Video Computer 4000, maybe that one sold even less than the OUYA in the end

You might be surprised at how much that actually sold. Nintendo Game&Watches sold over 43M units for example.

EDIT: Also, they’re apparently rereleasing them.