Recommend me a tablet for PPSSPP

[TkSilver]

In terms of pure performance there still is no competition to the Nvidia Shield K1 (except the Nvidia Shield TV). But that is just on performance in most emulators (not 64bit so no new versions of Dolphin) and gaming. Other tablets may be better suited to your overall use case though. To be fair there are a lot of tablets with better processors then the Marvell PXA1088.

But for the $199 (a lot of places most with no shipping some with no tax) there really is nothing close to the Shield K1