gpSP 0.9 (last official release)
gpSP Kai 3.4 Test 3 Build 152
gpSP 0.9 is the last official release by Exophase. It has since been forked and is inferior to said forks. It is generally recommended to use either gpSPmod or gpSP-J. gpSP-J has superior compatibility, while gpSPmod has more options for customization (full screen, cheats, etc). Both are superior to Kai.
This is the only emulator (or set of emulators, due to having so many forks) available on the PSP. The compatibility, however, is very good, and it is generally recommended to emulate GBA ports of SNES rather than the original SNES games as a result, due to the comparatively poor emulation of SNES on PSP.
Due to its development being focused on a comparitively weak console, gpSP is a good porting-candidate regarding emulating the GameBoy Advance to other weak systems. Emulators of the GameBoy Advance to the Nintendo DS and the Raspberry Pi are based on gpSP. Recently, Libretro added a gpSP core, bringing the strength of gpSP to more weak machines.