Wow. A six year old thread.
While I agree that enchantment has some powerful effects mostly at lower levels, a lot of creatures are unaffected by enchantments (undead, constructs, among others), as well as almost every high-level arcane caster (and those who have a high-level arcane caster friend), because of mind blank.
Other schools: Of course, the lower cost makes divination an excellent choice.
For school power, I would say in 3.5, conjuration is extremely good, perhaps the best, also having gained some spells from other schools to further increase versatility (for instance, teleport was in Transmutation before).
Transmutation still remains one of the best, as does Necromancy.
Illusion, of course, is very versatile, but faces issues with true seeing and mind blank. Evocation, IMO, got hit pretty badly in 3.5, and, IMO, the Orb spells clearly belong in Evocation (we have houseruled them SR: yes, as well). And although many state that direct-damage is not a good option for a wizard, especially at high (and epic) levels, when saves are relatively easy, the ability to dish out huge amounts of damage with metamagic becomes more and more important. Of course, Conjuration and Necromancy can do this, as well.
And then, of course, it all depends on DM, the theme of the campaign, as well as on the material available. In a core game, the smaller schools are a tough choice, unless your DM will allow you to do a lot of spell research. If you are playing an undead-heavy campaign, you'll want to avoid enchantment and illusion even at lower levels.