Some saturn games work at 60 fps without frameskipping, but 2d games mainly. For 3d games, using GlTools with 0.5x internal resolution helps a lot (Panzer Dragoon Zwei for instance is full speed, or layer section 2). But fighting 3d games in saturn are slow more of them, excepr the virtua fighters saga.
For PSX ePSXe is fine, or the core PCSX Rearmed in Retroarch, which has also a High resolution mode (it must be enabled in core oprtions). Using shaders like hq2x with Retroarch games look very good in a 5 inch screen.
For arcade, another choice is FBA4Droid, it doesn't support so many games as mame 0.139, but most important boards are supported, including PGM recent games like The Gladiator or Spectral vs Generation, that are not playable wth FBA Retroarch core.
I personally agree with Panja, I use Retroarch for almost everything (Megadrive cores are much better an updated than md,emu), except PSX that I use epsxe normally, mupen64 for nintendo64 and reicast for DC. Broglia's emus are also fine in general terms.
