Hi there. I’m a new RetroArch user (I just got a Nexus 7 and wanted emulators that were free but not crippled or loaded with 10 billion ads) and I’m a bit confused by all the cores available. In general, I’d like to know which cores for NES, SNES and Genesis (all of which have more than one option available) are the most stable and compatible. Also, is there a way to unload core that I’m unlikely to ever use? (VirtualBoy, for example) Thanks a lot.
If you have root access, you can go into /data/data/org.retroarch/lib and delete any of the libraries you don’t want/need.
For NES, nestopia is probably going to be the most accurate and speed shouldn’t be an issue on your tablet. For SNES, you’ll probably want to use Snes9x, as bsnes likely won’t hit 60fps. For Genesis, I would try Genesis Plus GX, as it’s very accurate, but if it’s too slow on your device, you might need to use picodrive, which is less accurate but extremely fast.
The next version of RA Android will allow you to uninstall cores.
Hey dudes not posted for a while but still loving RetroArch android on my Nexus 7 2013… Pissed off about Google Play removing the app from the store. Looking forward to the New updates 
I myself would suggest PicoDrive with games that were in Sega Consoles. I find easier to just mentally put them all together under one core.
About SNES, I read that higan is the most accurate, but SNES9X-Next is not only less laggy but also allows speedup (depending on the platform where you run RetroArch).
Higan is not laggy… It can be slow, but laggy is not a good term for slowdown
Oops. I did not know that there was a difference…