Ok, whatever, besides all the trolling. I just leveled a DK to 70 out of curiosity, gotta say, really OP. Just in full PvP Gear I can hit 7-10k Death Strikes on PvE people NP and I have like 17k HP. It's OP. End of story.
Rogue and Mage are both OP against OTHER CLASSES and mostly in ways that make those other classes feel powerless and frustrated when they lose. Some of them also lose to Death Knights, but they at least can do SOMETHING to them, or they can kite them, or ignore, things we can't as well. This leads to them feeling like Death Knights aren't as OP because they're down in the **** with everyone else, Rogues and Mages are like the Black Ops of PvP, NO ONE LIKES YOURS. You're the ******* cheap ass assassins, you cheat and lie and do dirty nasty things to win.
Rogue and Mage have both been at stages where they were amazing, and they've often been good, BUT they have had times where they were bottom of the barrel and some times just god awful, yet people STILL complained about them more than ANY other class. It's the playstyle. You lose to a DK, ok, whatever, he his a tank,etc...blabla, you lose to a Rogue or a Mage and you look like you're getting trolled just in the way they fight. They will always rage and hate and troll and beg for nerf to any kind of control style classes, no one likes to look like a noob as they get "outplayed" by a skill class.