The top three XPT posters are no-brainers: Monkey, James and Arab. In my opinion, this should not even be up for debate.

If I had to pick the top five, filling the last two slots would be difficult. Off the top of my head Bornyo, Burglar, Bishop, Guapo, ChickenMaster, Kyoto, Monstar, Have2cit and Coochie Monster could all fill them.
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"Bornyo sleeps under a bearskin that he killed and skinned when he was 5. He just stared the thing dead with mind bullets." - Floofin