Hello,
I've been totally unsure of what class to play for when Mists comes out. I know I want to tank. I played a warrior and bear druid as heavily competing alts all through the Cataclysm (I've been a warlock since the tail end of BC). I also have a blood DK, who is fun but I've never really clicked with the class and I don't enjoy paladin. I dabbled in the beta, and like most people, I tested out the monk class. I enjoyed the brewmaster spec quite well, so much so, that I piped up to my guild that I was most likely going to be switching from warlock to monk. They were fine with this, since my raid leader was aware that I would be switching roles to tank. After taking a few steps back I remember the DK swarm that happened when Wrath was released. One of my other guildees have decided to drop their rogue in favor of WW monk. I thought about grinding my toon to 90. The potential roller coaster of buffs and nerfs. I was suddenly not as sold on brewmaster.
Then 5.0.4 is released and I no longer find my guardian druid to be as fun...the play style is now tweaked just enough that it's not as entertaining. If I am tanking, I want to feel sturdy. I want to prevent as much damage as I can. How FR is now, just bothers me. I don't like relying on a flat out, reactive heal after getting blasted with some magic attack. On my warrior, I can actually mitigate. As it stands now, I really enjoy my warrior. I like the changes they made in the patch, I love the aesthetic and having a shield. So, after much debate I decided on prot warrior and I felt quite good about this.
I spoke with a guildee the same day. He said he would like to come back and raid with us. He wants to bring the same character he raided with in the past, a prot warrior. He offered to go dps (I know he vastly prefers tanking), but we need a second tank. It seems like a bad choice to have both tanks of the same class, with the same weaknesses and competing for the exact same gear. There is -going- to be competition, of course. And I feel like if I'm going to hurt the raid if I don't make the switch. So, now I have to decide if I am going to go through with the prot warrior, or go with the tank I currently enjoy second-best, the brewmaster. I am willing to make the switch.
For other reference, our guild is a 10man that does not have its roster for Mists of Pandaria totally fleshed out. We plan to down heroic content.
TL;DR: Returning guildee wants to play prot warrior, I do as well. Should I go warrior or monk?