Can't most Wii homebrew also load off of USB storage devices (e.g. flash drives)? Because I know I was able to run some stuff off of a flash drive. At any rate, a Wii is a pretty decent emulation/homebrew center for the price IMO, especially with the ability to use Nintendo's lovely Gamecube and Classic controllers.
If you are going down the Nintendo route. Wii - Only If you are interested in making the use of homebrew / emulation as well of the Wii games. Wii U - Only If you care about the Wii and Wii U games
After seeing a list of upcoming games for the Wii U I decided that's what I need. Yarn Yoshi, Donkey Kong Tropical Freeze, Mario Kart 8, and Hello Kitty Kruisers. Hell yeah!