After some consideration, gotta go with Fedtards really. Every time Federer loses or struggles against a low ranked player, it's because he didn't play well/is old and past his prime and, this is always added, there's no way prime Federer would lose that specific match, not to mention the cries for his retirement. Hardly any credit given to opponents like ever.
Of course it's not everyone, there are 'good' Federer fans, but his tards come across as the worst to me, or at least the most vocal (maybe because of their strength in numbers). To be fair, the claims from Rafa/Nole tards that their player is unbeatable on a given surface/when healthy/when he cares/etc... are no less idiotic and moronic as the attempt to elevate 'Prime Federer' to some God-like status, but not as prevalent on this board.