I don't like disintegrate even as a D3 spell, so would prolly not like it as a WoW spell either. Though I do like the Archon version of it as the Archon beam is a cone. But would say I would much rather have on the move instants for mages than rooting casts. We got enough root's to worry abt if they stick with T6 talents.
Other cool spells from wizards would prolly be explosive blast, magic missile(seeker), Hydra, Spectral blade(BATTLE MAGE ME WANT), wave of force, AE converted into Arcane torrent(death blossom, but just divided by targets stuff) and also D3 blizzard is 5 times better.
Also wouldn't it be sort of awesome to have Archon form as L90 option that buffs your spells sort of in a way that Avatar does for Warriors atm. Oh 1 can only hope..