I decided to start leveling my second character, I originally was planning to do it at level 10, but Rev Chris is 31 now. I wen't back & forth between Priest, Paladin & Warlock for a long time & eventually settled on a Gnome Warlock. I am so far happy with this decision & am loving the Warlock leveling experience. I just got my Voidwalker, named Hukthang, & the process of having to go into the catacombs under Stormwind to defeat a Voidwalker to prove I was capable of possessing one was a much better class quest than the Mage quests ever were. Okay, I admit the "Ghostbuster" mage quest was cool, but lore-wise the 1st two Warlock class quests were better.
I'm just starting out, but It's starting off better in every way than the Mage. Time will tell...
Reverend Sin with Hukthang by Reverend Chris, on Flickr
Welcome to the dark side. Classic Warlock is great fun.