My favorite is Myth. You can fight by yourself by summoning forth minions to aid you in battle and you can buff them or sacrifice them to heal yourself. Athough it is still good to fight in groups :D. My second favorite would have to be Life.
I like them all, but Fire is my favorite school. I like the spells, I like the colors, I like fire and I like red in real life, so I can't imagine not picking the fire school here. I'm usually happy with the results, in spite of fizzle.
Personally I like Life. Even more so now that I have my own minion. It's tough to get off the ground, but I picked Myth as a secondary school to offset the loss of outgoing damage. I run around with an ce mage a bit, so the healing as well as damage are balanced well Plus I just like healing other people. POWAH TO DA UNICORN!