My favorite class would be the binder, I just love the fluff. The mechanichs are pretty nice too, allowing for lots of customization and allowing for at-will effects most people can't have. I hate the vancian casting system but I like versatility and cool effects, as well as a bit of occult mixed in. My second vote goes to psion, I love the way psionics work in 3.5 due to there fluidity.

My favorite race is Elan. Just like there fluff and immortality. To bad they don't work that well together with binders.

My favorite spell? Hard one, I don't use spells that often, I'd say it would be... Extract Water Elemental, from the Spell Compendium. Not because it's good, far from it, but because I so love the flavor of it.