I'm trying to get into running sms and I'm not sure what system to purchase to play it on. Should I buy a Wii or gamecube or just run on a emulator? What the advantages/disadvantages.

NTSC-J Wii and SMS Disc

lol you don't need a japanese wii

homebrew requires stuff like USB/SD and thats banned

USB loading and SD loading is banned. Homebrewing your Wii to allow region freeing isn't whatsoever, as long as you use don't use any Homebrew to load the game from something other than an original disc.