Another poll? Another poll where selecting a single option doesn't suffice: There are many very good emulators on the Wii.
The Wii is my primary emulation machine for older Nintendo hardware. (S)NES is next to perfect. I've yet to find a problem worth of mentioning. The same positive things can be said about mGBA for Game Boy Advance titles. The already mentioned sound hiccups was the reason for not continuing usage of VBA GX.
The N64 emulators do not convince me, so I stay with the real N64 for now.
I find many appealing points on Wii: Fast boot time, ease of use, many very good emulators, 100% native GameCube support, very good protection against softbricking (BootMii@boot2). These reasons make me prefer the Wii over the Wii U (which I use exclusively for Wii U games; did not even bother with modding vWii).
If I'm able to concentrate a little more I will try to correctly set up Retroarch on the PlayStation Mini to see if it can be a good alternative.