My list based on who i see regularly, I've no idea on the activity of players like animosity,dashto, 'athena etc who would certainly have made the list
Sage/sorcerer- Exa'dal, rilana, baarf, dominance
Shadow/assassin- dizeren, faatt, peb, claws
Sentinel/marauder- Catheana, Hikarie, Mahina,
Guardian/juggernaut- Ulliam, zerkonis, cerin, rytan
Gunslinger/sniper- Gucci, O'pii, dock, tsuranai
Commando/mercenary: Severin, Dimitrios,
Vanguard/powertech: Jerc, Courmac, (im forgetting someone REALLY burny here and im sorry)
a bit more of a breakdown on something i know better (no particular order)
Scoundrel/operative heals: Tor, Nollie, Jackobie, defribula (I'd like to think I'm in the conversation somewhere too)
Soundrel/operative concealment: Cancer, Luddott, Source
Scoundrel operative lethality Tor - he's the only player I've seen make the most of this spec.