Necrons for sure. Of course, everyone is entitled to their own opinion and taste, but I find Necron supporters to be rabidly vocal. Check any Dawn of War forum or youtube comments section and you'll find an endless stream of people begging for Necrons to be a playable race. Even on the Battlefleet Gothic Armada comments, people are demanding Necrons to be the next playable race (it'll be Tau though). They are fans beyond sense and reason. How can Necrons be part of such a game when they barely have any variety of ships?
Hmm...so perhaps my issue isn't with Necrons, but with Necron fans. OK, I change my vote. Remove Necron fans from 40K.