1. Frost DK is a very very good spec through the expac basically until ICC (you could argue ToC as well) where it begins to fall off relative to the field because it simply doesn\u2019t scale with Armor Pen as well as the other classes do. So power-wise, it\u2019s a very solid choice for at minimum 2 to 3 of the expansion\u2019s raid tiers.Fun-wise, I think it\u2019s quite fun once you learn the rotation. It\u2019s something like (operating off of rusty memory here, not promising it\u2019s 100% accurate) apply diseases -> obliterate -> frost strike -> blood strike to make a death rune -> obliterate -> frost strike -> obliterate -> frost strike -> spend a death rune to refresh both diseases in one button -> repeat from the first obliterate.2. Combat Rogue is as it always is. Assassination becomes very fun if you enjoy a very flowing rotation where you just repeat the same loop every 5 seconds or though to infinity. Although it\u2019s completely non-viable right now.3. Ret is strong. It\u2019s just strong in other ways. It\u2019s amazing in open-world PvP, only having a few truly losing matchups 1v1. However, it suffers in arena from not having an interrupt in an expansion where healers do a ton of health per heal. Maybe you can get some WotLK Items instead.In raids, it has amazing buttons like Salvation (20% threat reduction over the course of 10 seconds on whoever you use it on), sacrifice (giving someone else a free defensive cooldown), Dispells, BoP, replenishment (tons of free mana to everybody in raid - an absolute must have from Ret or Spriest), you get the idea. This is however balanced out by them never being a top dps spec in terms of personal damage done, and they\u2019re particularly bad at certain points like Ulduar, but by ICC they\u2019re very respectable damage. T10 does a lot for them, it\u2019s their best tier set by far.4. Fire mage ends up as hilarious fun with 50% crit chance pyro proc rolling by the end of ICC, although you play Arcane for most of the expac. I wouldn\u2019t call Arcane particularly fun gameplay but if you like it then all the power to you.