I like Newegg because they have a bunch of pictures of each item they sell. When buying a case some websites have 1 or 2 pictures, but Newegg usually has at least 8.
Newegg also has reviews by people that have purchased the item. Sometimes bad reviews need to be ignored because the perosn didn't know what they were doing, but otherwise a good tool for finding what you want.
I have also heard that Newegg is very easy to deal with on returns even though I have never had to use them for that.