As time passed, things changed and hence here is a new list of best in class, as seen by me, a random subpar battleground atendee.
Alliance / Horde
Mages: Gnomuch / Heavenwaits
Gnomuch is the greatest WoW player that has ever lived. This comment stands as it did almost a year ago. Despite the many jokes and memes Gnomuch and Brattan, are quick, determined and decisive. His lack of the grasp over the English language often lead people underestimate both his skill and character. But he is a superb player with a lovable personality.
Heavenwaits is the best horde mage even though he faces stiff competition on hordeside. Heaven is a smart player, elusive to the point of myth, doesn’t indulge into rage debates and plays for the game objective, discarding petty personal fights. He is a true asset to any team who can change the course of the game.
(honorable mentions on alliance side to Falladan and Hordetears with Gankuskhan being a future dark horse of this competition. On horde side honorable mentions to Spritzor and Glimpses, and in newer times Imagenon. Spritzor is technically very, very good, and Imagenon is a strong FC, but they both lack the completeness of Heavenwaits).
Warlocks: Frakt / Conspirazy
Frakt has been second only to Bazzaroth. With him out of the picture, he is the best alliance warlock.
Horde has a lot of good warlocks, who all lack the decisive edge to be called the best. Some are horribly strong but don’t play often. Some are strong, but not superb, but do play often, and when they do, they can really make a mess of the alliance team. In this regard, I would deem Conspirazy to be the best in class, although (to our tactical relief) he has not been online so often lately.
(Honorable mention to Cakemonster, Mudcorrupts, Aranddur and Reassons. All of these can wreck havoc in alliance lines, especially when the two combine together. Gemini is a future dark horse of this category)
Shamans: Darktyrant
Horde has a lot of devastating shamans and it is again hard to pick one. A T3 shaman is a weapon which does not fail easily, but even in these circumstances, one has to choose the best. I have chosen Darktyrant because of his tactical versatility. Although he can deliver massive punishment to the alliance team in form of damage, he does not shun from playing defence, fcing and such. A close second, based on the same grounds is Orcfromdeep, but as he is best in class of another category, I have given the advantage to Darktyrant.
(Honorable mentions to Telluz and Indez and Shammerd whose damage output is equal of that of a raid boss).
Paladins: Renovatio
He is the best paladin I have played with and in my opinion the best overall PvPer on the server. He is a game changer in any situation.
(Honorable mentions to Mlatek and Aixa. They fight a good fight. True knights of the Alliance. Their tenacity and resolve would lend them best in class in any other situation, were it not for the large shadow, Renovatio casts).
Hunters: Inya / Abitcoin
With Krey not playing the title of Alliance best in class hunter is up for grabs and the prime candidates are Inya, Sufix, Roosho and Sentinnel. I have chosen Inya because of his methodical approach, calmness in the face of danger and general mild and cooperative demeanor.
Abitcoin is the best horde hunter, and whoever organized the Garonna-to-Abitcoin trade has done more for the Horde then Grom Hellscream and Thrall combined. Abitcoin could be in the same conversation as Mamooko for the position of the best horde FC.
(honorable mentions to Sentinnel, Sufix and Roosho, as all of them could easily be best in class. It was a game of inches on alliance side).
Warriors: Tinyslam / Ailif
This is a hard category because the best three warriors on the server play both alliance and horde: Tinyslam, Rectal and Complexity (or Calmplexity nowadays it seems) who when they win two in a row (or when i que for an easy win) switch to Rinser, Ailif and Cumplexity. So basically the choice falls to 2/3, and in this case, although I respect his skill immensely, Complexity gets the shortest straw. If there can be only one, then we have to take into account the immeasurable tactical assets that Tinyslam brings to the table, who is the best tactician alliance side. Also there is something to be said about Ailif’s tenacity and stubborn resolve which has, in this list, lent him the top place.
(honorable mentions here to the rising star of Ashenvale Jvgg, also to Dawayne, for whome Napoleon had said: “You win battles with infantry, wars with artillery and Alterac Valley with Dawayne, Xyhpa – who is the best warrior FC, and Sladey who is just a joy to play with. Dark horse of this competition is Eblolom, who may enter this list in the future).
Rogues: Saesenthezis / Anarchi
The alliance best in class rogue contest is between Massmurder and Saesenthezis. It is a close one, but Saesenthezis ability to command as well as slay has given him the edge here. On horde side, honorable mentions are Undacava, but as he is such a large part of Anarchi’s life it’s hard to view them separately and Elizabeths, who is not online so often.
Druids: Chocolad / Mamooko
Mamooko is the best in class but has not been online for a very long time. Still it’s hard to not deem him best in class, when he is in fact best in class. Honorable mentions on horde side go to Saxi and Sandmooa. On alliance side to Kerlara and Decapitated.
Priests : Labyssa / Kleanix
The veteran favorite Boltzman has not been online for some time. But in my opinion ha cannot be best in class due to the highly uncooperative behavior he sports. Chou is a very good player and so is Dalilka. Labyssa is widely criticized but I will go out of my way with this proposal and call them best in class priest. Despite some questionable moves and strategies, Labyssa has a lot of kills and battlegrounds under her delicate silk belt, which can, at least in this humble post be honored. Kleanix is the best horde priest. Honorable mentions to Assanaris who is the only viable priest fc on horde side, Anolfia who is the most pleasant priest to play with and Yungsung, who is always there.
This is all of course my personal opinion, and we are discussing here only "the single best". There are much and more great players on both sides in wsg, and each of them would not be out of place if put on this list.