I'm personally a big fan of /sch when it comes to bst/mage. There are many pros, with very few cons. You get pro, shell, reraise, cures, -na spells, most defensive spells, save for phalanx, as well as getting access to erase and dispel if the situation calls for it. In addition you get grimoires to cast more efficiently, and stratagems to augment your spells. You also get sublimation and aspir to keep mp up. Very often, particularly in WoE, I can keep myself going almost indefinitely with just drain and aspir. Now it's not the sub for every situation, but it is one of my favorites.