I like creative and unique usernames. For example, my username came from a old username on Dailybooth called AaronWhatAaron. I realized that was way too long and shortened it to AWsquared which is shorter and more creative in my opinion. Anything more than 3 words is too long and is hard to read.
Also like usernames that sound like they could be actual names. Such as Sydian or Kouzan, the username I've been using on other forums.
Some names I really like on PC are BinaryPeaches, Sydian, Forever, Requility, Ausaudriel, Minzy, Toshiro , Sylphiel , Abnegation, Mr. Cat Dog, Aerilyn, Patchisou Yutohru.
Non PC usernames
Mintaka, Bikini Miltank, Avartus Cantus , Archaic , Neon Borealis, Dragonfyre, Ghetsis-Dennis , Goodbye Blue Monday , Aeralis , Ange Serena, Satoru Asahina, Wishful Thinking, teamVASIMR , Bouffalant Herdier, ghaskan, Eitarou, Dogasu.
a very long list...