I'd get the Evo over the shift, but that's just me.
The bigger screen and greater feature set make it worth the price of admission. Though, I wouldn't get either at this point. We are way too close to Sprint's Q2, and Q3 phones, which will certainly smoke the Evo and the Shift.
Whats this a new model around the corner? Any more specifics?
but to answer your emulator question: I've seen iPhone and ipod touch users connect a Wii remote to their phone (i assume via Bluetooth) and they can play emulators through the remote! It's great because you can use original nintendo controls for nintendo emulators. I'm not sure how to connect for android, but look into that for the Evo!