I've used this 128GB thumb drive for maybe two years and I haven't had any problems:

http://www.amazon.com/SanDisk-Cruzer-Glide-Drive-SDCZ60-128G-B35/dp/B007YX9OGW

I just feel a thumb drive is simpler, cleaner looking, and requires less power. Hard drives seem to be the preferred method, but as I said before, I haven't had any problems with my thumb drive.