SSF is the best emu I've used. Plays my games and ROMS well.
If Sega put the original Sega Rally on XBLA for 1600 MSP, I would hit it up in a flash.
I'd also pay that for pixel perfect ports of Daytona(not CE), Dragon Force, Burning Rangers and Sonic Jam.
Add Sega Touring Car if they get rid of the contextual steering.