For gaming at great price, A620 period. However, if you have money, A716 is a well rounded PPC that is as fast and has extra ion battery, internal battery and a nice pad, and if you're planing on intensive emulation, either you get a massive battery like the A716 or you will only get about 1 hour of gaming on the most demanding games.
However MAME is not very demanding, so I suggest A620, it's really the gaming PPC at this time: fast / cheap / great button layout / CF slot / best PPC pad of them all
I haven't played Starforce, but tried some others like bomb jack, space invaders, frogger and others, worked great, though I couldn't configure correctly the buttons (however I didn't try much, I'm not much into retro gaming, but people on MameCE forums had the same problems and seemed to fix it, check them out). The good thing is that some of those games only used one or two buttons, so it wasn't much of a problem.
