Warrior is my main and I'll probably never switch. I have 2 Monks and Warlock at 90 too, but don't do much with them. I'm leveling another Warrior and a Shaman atm.
BC was Hunter
Wotlk and Cata was Ele Shaman
Mop was Spriest
WoD..not sure if I'll even play I'm learning towards Resto Shaman
Mage since I started playing, got a 90 mage alt too, aswell as lvl 90`s of each class.
My Hunter since I began in BC. I play everything else, too
I never get bored playing a shaman xD
Its so fun, no other class comes close imo. In fact, my DK is the only other class I've bothered to level to max.