It supports SDHC cards now, and you could get yourself a 32GB card if you want. I would prefer a 4-8GB card. SanDisk or Lexar if you go by quality. Don't mind different speed on those cards and everything, it's useless.
Non Wii brand cards fucks up your console? :lol They're made by SanDisk and it's just a regular SanDisk SD card with the Wii logo on it....nothing else.
He was just joking. Time to check those sarcasm detectors!
An 8GB card, or even 4GB, should be more than enough for downloading whatever you want. I have a 4GB one in my Wii now (hot!) and have about 50 VC and Wiiware games on it, and I've used like one tenth of the free space one it.
Buying a 16-32GB card would be overkill as you'd never ever fill one up.
I have a standard 2GB SD card for GHWT DLC and a 4GB SDHC for VC/WiiWare. I only swap cards when I play Guitar Hero, so it isn't a big deal. Hopefully GH5 and other future DLC games will be SDHC compatible.