Launchbox supports everything, it doesn't care what the emulator or retroarch core it is, it just loads what you tell it to. The most accurate so therefore best in my eyes snes cores are the bsnes and higan cores, but they need a good newish cpu, around about a i5 at 3.2ghz or so, snes9x is fine and will run on lower powered hardware, but is less accurate. I personally use higan which is the most accurate and needs the most horsepower, I have a i5 3570k overclocked to 4.2ghz and it works well.