Best Android phone to emulate PPSSPP

[geigermuller]

The best mobile gpu in the market right now is probably the powerVr sgx544 found on the international Galaxy S4 and on the iPhone. The Adreno 320 found on the HTC One and several snapdragon S4 phones is also pretty good. And finally we have the upcoming tegra 4 gpu, which will supposedly be the best, but tegra has had a history of being excessively hyped and marketed by Nvidia.
So in short, a phone with any of these gpus will pretty much guarantee that you can play nearly all games at full speed once ppsspp becomes more polished, perhaps in version 0.8+.
On the other hand, phones with older gpus will probably also be able to play most games well, but only after ppsspp is fully optimised, though that might take a while.