You'll get a few dozen different responses. It's all about personal favorite and preference... one of the better ones I've seen (and the fastest one on the market to boot) would be the LaCie Two Big, though it's uses other than for personal use (as in don't expect to be bringing it to a lot of people's houses as they may not have the right hookup for it).
http://www.lacie.com/products/product.htm?pid=10775