I remember wanting a Nomad. The only home console I had was a Genesis up until someone gave me a PS1. When I was really young, my favorite games were Sonic 2, Sonic 3, Tinhead, and Vectorman. I still play them with an emulator on Wii. A friend of mine had and played Nomad last I talked to him...although he used a 12V sealed lead-acid UPS battery and a 9V regulator to run it. It was hilarious seeing him play it at university last year with that big battery on the table and a backpack full of genesis carts. Sucks I didn't own a decent phone until about 4 months later or I'd have a picture. Technology has come a long way...
Gameboy Color shouldn't even be on this list. I had a GBC (was what I got instead of the Nomad). I played that thing for hours on end on long car rides. Tons of games for it, and GB games were compatible too.
I can't speak for WonderSwan or NeoGeo, as I've never played either of them. In fact, until this post, I'd never heard of WonderSwan. That tells you how well it was advertised and how much it's talked about nowadays...
VirtualBoy wasn't a total flop. A friend had one, and yes, it sucked. Gave everybody headaches and the rest of it left something to be desired too, but even today there's still a following for it.
That can't be said for the Tiger stuff, which is pure junk. R-Zone got my vote.