I really kinda wish they'd take Taxman and Stealth's iOS port of Sonic 2 and use it as the basis for the 3D Classic, but I know that will never happen. At least we have Taxman Sonic CD on consoles. <3 amazing game, that is.
Streets of Rage 2 is a game that I don't think is worth playing unless you have a Model 1 Sega genesis's headphone port hooked up into your stereo and subwoofer. I suppose maybe it'd be cool to play with headphones and in 3D?
Gunstar Heroes is tempting, but i have to wonder if it's going to be possible at all to play the two player mode at all. that game BEGS for co-op play.