I cannot play a Paladin to save my life. To me they are just too complicated with the seals and stuff. I tried. I got to level 8 before giving up. Mad props to anyone who does but as for me, I just can't.
I also can't play a Warrior either. I have no taste for it.
I like my Shaman but I don't much like the enhancement spec that I just switched to for easier leveling. (And it really is easier to level with.) I really like my BM Hunter. I'm kind of apathetic towards my warlock and mage.
I've never seriously tried a priest or a druid.