That T8 does have 2 Analog sticks like the Vita, which could come in handy for some Andriod FPS or OnLive Games, and also usefull for any PC ports just as Quakes, Dooms and Duke Nukems etc.
Depends on price, build quality (controlls, screen) the Specs and off course the OS i.e Andriod version.
The JXD s601 looks like its doing well, ticks most boxes, could have done with HDMI and Dual Analogs but apart from that its hard to knock the device.
The upgrade YDP looks decent, ok maybe the SOC/CPU is not a major upgrade, but more responsive screen and Andriod 2.3 are good improvements.
However its hercules heel could be price compared to the JXD that being $150 compared to $90 now price would not matter if the YDP proved to be better built, less buggy and higher spec but really there is nothing or little in it, but there is a big difference in price.