I would say an argument could be made that he is. Note, I mean, WORLD OF WARCRAFT, not Warcraft II, not Warcraft III, WoW the MMO. You hear a lot about how Blizzard famously butchered great characters like Illidan, Kael'thas, Deathwing, Thrall, Garrosh, Grommash, and most recently, Anduin, Sylvanas and Saurfang (Baine was always awful IMO.)
We got an Illidan redemption story, and we read threads all the time about people wanting Kael'thas back... yet, we never get Varian resurrection threads, which is a good thing, right? Aside from the Knaak stuff, he was probably the best written character in the game. Suffered loss of his father as a child, his city was sacked by Orcs, he was Thrall's slave, was blessed by a Demi-God, bad ass gladiator, lost his wife, came back to re-claim his kingdom, was able to raise his son, was hateful towards Orcs but learned to let go of his hate, killed Onyxia, and finally died heroically, for the Alliance. Even if you don't like Varian, is there really a notable WoW character who has been written better?
Tirion was only prominent for one expansion. Khadgar's journey isn't over yet. I can't think of one, can YOU?