RP - hmm,maybe,but maybe LN,official Corsairs(in Gamma...and around)
PvP - "old" dudes from [TBH],Indians,Avengers,TCG,SMP,Sails, a couple of dudes from XTF,[RHA] huh! :D
In my opinion, no faction is consistent enough to offer either the best RP or PvP.
However, during my time here, I have found that most people are consistent about being RP or PvP focused. Generally everyone has a style that they abide by, kinda makes it possible to tell who is behind the character you are interacting with.