So i am trying to figure out who would make the better MT for kara. It is between myself and a warrior in my guild.  I have about 5-6k more armor and more dodge.  We are both uncritable but he has a defense of about 480.  Im being told that i have to be the OT. Who would actually make the better MT.

Ferals make excellent offtanks

warriors, are the best tanks for single targets such as bosses because they tend to have the most TPS and the most dmg migitation, feral druids make excellent off tanks because they tend to have the most armor/health, and paladins make excellent aoe tanks, on pulls such as the aoe pulls on the way to moroes, because they can hold aggro on all of the mobs and at once, and they can simply be aoed down

that being said, any class can tank any boss, mob, or pull but some do it alittle differently than others

Your warrior shouldn't be MT'ing kara without 490 defense to become uncrittable.

I have  level 70 Druid and I MT Kara all the time. It's mostly the warriors now that OT with me lol. It doesn't matter which one tanks, as long as you know what to do and you have the gear to do it.
I saw go for being MT a few times then swtich then your guild can decide whos better.