That'd depend on the platform. I keep pushing GME, but that's a library, not a player. Try something that uses that? (Or its standalone NSF emulation library, on the same page?)
Actually, droidsound's nsf library is GME. And looking at it's site, GME doesn't support MMC5, FDS, or VRC7.
Sorry for the bump, but I recently asked the creator of NES.Emu about adding NSF support to his mobile emulator, and he said he was thinking of making a standalone chiptune player that would cover multiple formats on the same platforms all his emulators support.
He also said that preliminary NSF support was on his to-do list for NES.emu.
If he decides to really do all that, It would be pretty damn awesome to have an NSF (and other formats?) player that runs on android and isn't buggy as all heck.
