Both of these systems are neat emulators that can play some classic games. Do not expect them to do any type of modern gaming.
JXD advertises that their JXD5000 can play Playstation games. It can do that, but not well enough. The PS1/PSX games feel slow, and after testing three popular games I concluded that it cannot play them well enough for them to be enjoyable.
The JXD5000 can play some arcade games which work very well. The system includes a few games like Metal Slug, Street Fighter Zero 3, and Rockman X5 (megaman in the USA). The animations are smooth. I did load these games onto the Dingoo and they did NOT work.
The Dingoo can play some 3D games which are made by Dingoo. They are not "epic 3D hardcore" games, but they are nice for a casual game session. (wiki has the list)
Both the Dingoo Digital A320 and JXD5000 can play Game Boy Advance games which has been my main usage, but they can also play other systems.
These are the advertised emulators:
There are modifications and more emulators for the the Dingoo which can be found with a few google searches. I haven't heard much on this about the JXD5000.
Personally I like the capabilities of the Dingoo A320, it does a fine job at those classic games. The JXD5000 can do a bit more intensive stuff, but I still wish the Playstation games worked properly.