I'm not a tank but as a mage I still stack strength because it effects blocking. So definitely strength for your blocking and such. Mnd for those weapon skills which require mp I believe (i'm going off my bf right now, he tanks not me, but he doesn't talk in the forums), hopefully a die hard tank guy will come in and give you a rundown because they hated how awful my explanation was ^^ I'm not sure at all how useful dex is in tanking and I can't get a solid answer from anyone, so hopefully a supertank has some parser data.

I think you should ignore evasion, i think thats more for pug tank