I've heard great things about the GCW Zero consoles. They appear to be easy to develop for, well built, and long lasting. Which is more than I can say about a lot of devices I've seen sprout up over the past few years.
As for me, I had a JXD 7300, but sent it back to the company because it was problematic.
With a little bickering, I was able to get a JXD S7800b back instead, which from everything I am hearing, is a major step up from the 7300 featuing improved specs, better design, and high compatibility. Apparently I can run both Dreamcast and PSP on it not to mention DosBOX at very high speeds...
....that's a sale to me.

Mine should be in tomorrow if the post office gets its butt in gear. It's already two days late. Grumble grumble.
http://www.willgoo.com/jxd-s7800b-game-pad-quad-core-rockchip-3188-ips-lcd-8gb-p-356.html