Double post for a sugestion not that common but in my experience better than generic geo/brd/cor.
Surprisingly, i noticed there arent that many tanks proportionally.
And while you will always need suport jobs, it should be obvious its the tank who dictates the fight course. You can have ***suports, ***DDs. The worse that will happen is you timing out. But if you dont have a good tank, regardless how good are your DDs and suport what will happen is a bloody carnage.
So, its always useful having a good tank available. And a good tank can be achieved if you: can survive, can kinda of survive by yourself without depending on healers cures, and can maintain the mob attention.
Another good point of good tanks is that gives time for the party to get used to foe and learn how to do better, what certainly wont happen if your tank dies on first move.