WORLD of Warcraft.
I have a 60 Mage, Troll. Went to Iraq and lost the ability to play (I ould play with lag, but mages don't handle lag well).
I'm just going to start over on Warhammer: AoR.
EDIT: TO level fast and consistantly, just grind. Grind, grind, grind. Do quest that require grinding. Then grind some more. Group up and grind instances. Then grind.
You'll hit a hump at 40-50, then again at 55-60. Not sure how its goes above that. But, I assure you, grinding will get you up there. Just remember, never stop grinding.