My 2 cents for what it is. A lot based of WSG mostly, not enough AB played to tell other stuff.
Horde
Rogue: Xposed, Sushibarf. Dextros (doesnt get credit cause troll)
Priest: Lubbo, Crucial, Silvah
Shaman: Grabthar, Whameradetu... both know how to offheal as enhancement. Can run flags if needed, peel, and not just play offensively.
Mage: Ispod (best peels). Ayz, plays fire well, can carry flag well and kill efc a lot of times solo. Sometimes gets carried away when he has flag and goes for efc but its k.
Warlock: Lharts.
Hunter: Reaph, can defend or carry flag if he wants. Can peel as a hunter always good.
Warriors: Callow, Minoan (best engi user), Rxr (best peels for his heals), TrotaNOOB( no epic mount )
Druid: Yo de Burnnnnnnn (enough said). Badgemagus plays well too but doesn't have support all the time.
Alliance.
Rogue: Zidanelol, jacknifex, perp (when he isn't trolling), budweiserx (itsreal). Zze.
Priest: llureev (starting to get geared now too gg). Sachikomoe (happy you still find time to play some bgs). Toluca (Once gets gear will be even better). Pibie (inactive)
Paladin: Strombald one of the few ret pally's that you dont get mad at for being ret. Icarius not as active anymore though. Sulfura plays very good too.
Mage: Not as active anymore but Shatter, Yolam, Madgetegame all good in no order. Spuudre knows how to peel and run a flag.
Warlock: Rains (nice nades), Edhris (uses pet well).
Hunter: Sarei and kaulre* (misspelled) both fc well and can peel too. Timecop was good when wasn't afk farming gold on different account but also inactive.
Warriors: All warriors that I think are good are inactive in the pvp scene atm Crypton, Worstwarrior, Khamazandu. Nedstark is good but doesn't get love cause of haters.
Druid: Capture is a beast. Changes his gear setup a lot during the bg. Uses engi items and blacksmithing trinket well. Honorable mentions: Cowloverx (once he gets more gear gg), Germionka (._.), and Stormlling (get a mount).