No particular order:
ScrewYouGumby2 - Very underrated player and the one of the best I've seen.
CraftyKratonite - Just because how fast he evolved into being a great PvPer.
G33ke - Quickest and fastest PvPer I've seen.
ZenoCrafter - A no brainer to put on the list, very good.
SixZoSeven - Another no brainer, also a great PvPer.
egrodo - All I can say:
http://www.youtube.com/user/Egrodo1
3Crowns - An old timer of course, and my idol.
Blamph - Another old timer, not as good now but back then a tank.
Ryan - Of course a very good player as well
LeafyGreenTea - When I saw his famous video, I was like "I want to be as good as him". It never happened but I'm getting up there. I mean he was so good he got banned for "hacking". Idiot mods.