Ultimately, whatever is the best for you will follow along with your playstyle. From your description, it really seems like you're more defensively minded, so I would go with Champion or Templar. Champion is the true tank spec, while Templar has a lot of party buffs and support. Templar is still a good tank, but doesn't have the same tank-specific tools that Champion does.
Don't forget that one of the hallmarks of tanking is making smart use of taunts, knockdowns, and tools like grappling hook that pull enemies away from your friends. One of my favorite things to do as a tank is to charge into a group, hit the AOE taunt, and also grappling hook an archer or mage. This keeps everyone on me, allows me to build guard, and clumps up the enemies for some nice AOE.
I do understand that dealing with the AI in DAI can be frustrating, but you can somewhat control how your followers react by adjusting their follow/defend setting.
One of the more helpful posts about this I've seen:
Follow self means they choose a target and keep attacking it until it's dead, no matter what you attack or what attacks you. Defend makes them stay closer to you and, attack whatever attacks you. Follow Controlled makes them attack whatever you attack.
As for keeping them out of AoE, Fires and at range, some do better than others at that but, none do very well under AI, just have to set the health and potions remaining limit to allow for it. Varric will use leaping shot and fall back a lot once he has them. Sera is bad for getting too close. Vivienne won't use KE, won't Melee even when she has the skills unless you disable all other attacks for her.