AOE Knight's rely heavily on stamina for their tanking abilities. For the best build you are going to want to have high stamina and a small amount of strength.
For tanking a lot and also for soloing:
Strength: 50 (cap it this)
For more damage but also tank-ability, cap strength at 50 when you are level 65 and then get stamina to 110 and go back to pumping strength:
For Insane damage but complete reliance on RMs:
Stamina: 60 (this is the absolute MINIMUM you need. Anything below this will make it impossible to aoe effectively if at all.