This is a follow-up from this post in June, and you should watch that video first so you know what Preach is talking about and you're able to follow along with him in this video that I embedded below.
Did you pay attention to his reasoning? He chose to raid as a Mage according to criteria that allowed him to be the reliable team-player that he finds necessary to be a successful raider, tempered with the realities of his life away from the game, and further informed by his sense of euludos and aesthetics.
If you follow his process, you will not likely arrive at the same conclusion. I will raid as a Warrior, again, maining Fury- as I have since Icecrown Citadel in Wrath of the Lich King and keeping up a Protection offset for when the raid needs a third tank. Arms is not a priority for me, but I'll keep up that Artifact on the off-chance that Arms is worth playing over Fury. Also, I raid as a Female Troll; troll melee animations haven't been a problem for me for over 10 years, and not changing yet.
So know your circumstance and your preferences before you choose so you can make an honest, informed decision. Your teammates will thank you.