I suggest speccing FDCL for Garrosh, since this fight actually has a ton of movement, at least the way we did it.
Our strategy was moving in a triangle pattern to deal with the desecrated weapons and mind controls as shown in this picture I quickly drew up:
Basically the group starts at Yellow marker. When Desecrated Weapon is thrown there, we all move out of it and stack on the boss (purple marker). The Mindcontrol will follow almost immediately when we get into position. This allows for everyone to be stacked, and we can deal with them fast and easy with stuns/cleaves/interrupts from melee.
When MC is broken, we move to the Red marker in preperation for the next weapon. When that weapon spawns, we move to the yellow marker to stack for the Whirling Corruption. we don't want to be in melee range for that, since it does damage based on proximity.
Doing the fight like this made it quite movement intensive, and I found FDCL to be the strongest choice, after playing around with both that and insanity. FDCL is also nice when in the Sha Realm and dodging annihilates.
There might be a more efficient way to do the movement where Insanity gets to shine, so if you know of any, feel free to share :)