MVS, CPS1, CPS2, and (sort of) GBA emulators work better than the Sega Genesis and Super Nintendo emulators? DGEN has numerous compatability issues (Adventures of Batman and Robin, Sonic 3D Blast, X-Men, Landstalker, I could literally stretch the page with this) and doesnt support the 6 button pad (The options there, but it doesnt work), and SNES9XTYL requires ME audio (And the version that doesnt really isnt worth it), which disables the sleep mode (For those of you going NO IT DAWZNT, all its doing is turning off your speaker, screen, and clocking down. Its a pseudo sleep mode). It also has speed problems with various games (Super Mario RPG, DBZ Hyper Dimension, all the Donkey Kong Countries, just to name afew).
Granted, these emus WERE created a while back, and the devs didnt know nearly as much as we do now (Or so I assume).
I cant code worth crap (Or, rather, I've never really tried), but I'd just like to point out that both of these emus are open source. Begin flaming of the topic creator for not appreciated what he has (I do really, its just that it could be so much more at this point in time).