I've been very happy, and impressed, with Great Lakes's RP.
As to high-end PvM, the Ilshenar Champ Spawn crowd has been both nice and competent. I also have fun doing the Tokuno Champ Spawn since ToT3 came out. I have no idea yet about Peerlesses or Doom, as I've been preoccupied with RP, EM events, Spawns, and ToT3 since I came over.
GL also has great Event Moderators.
I used to be on Lake Superior, and it was decent for high-end PvM. There are these Community Hunts that do different things (they organized Ilshenar Champ Spawn hunts before Champ Spawn Artifacts came out, and they do a Peerless a week, among other things). The Ilshenar Champ Spawn crowd was, like GL's, both nice and competent. Peerlesses were done fairly often, and sometimes folks would even invite in a stranger.
-Galen's player