Riley is the gift that keeps giving. I know some people might think she's your average run-of-the-mill Tumblrina, but she's done so much shit in the past (there's a lot of stuff that still needs digging up) and continues to do shit today that you really can't place her in the same category as the others.
Plus, Riley was kind of the proto-SJW. A few years ago she was really shocking because of just how nasty, spiteful, petty, cruel, and, most importantly, influential she was (her followers weren't referred to as "Riley's Army" for nothing). Now people on Tumblr with those traits are a dime a dozen, but she kind of pioneered the whole "be a huge fucking asshole on Tumblr while using social justice as an excuse" thing.