The Lord of the Rings is probably the closest relative to an ideal Warcraft movie, I'd think, and Andrew Lesnie worked closely with Peter Jackson to shoot all of those movies. Bruno Delbonnel is another choice -- he not only shot Amelie and the latest Harry Potter, but he's been Oscar nominated a number of times. Wally Pfeister has worked closely with Legendary Pictures (who are producing the movie) and Christopher Nolan, shooting both of the latest Batman movies and The Prestige as well.
As for music, you'd think that there'd be plenty of Warcraft music already, but Hans Zimmer or Howard Shore might be two ideas for composers. After that, I don't know -- who would do costumes? Effects? It'd be great to have Weta or ILM working on creatures for the movie, but then again, Blizzard's CG team really should have a part in it. Lots of potential all around: if you were hiring the crew, who would you choose?