After a brief playtest, I've decided that the build benefits more from Defense fighting style than Great Weapon Fighting. GWF is as good as I thought, but it is a luxury to do a little extra damage, whereas any constant boost to AC for this character is strait up gold.
This is what I decided based on creating synergy and getting the most out of class features, rather than stacking redundant bonus actions. What I wound up with is a Cleric that can hang in melee and dish out some significant damage with their weapon. Pretty good AC between heavy armor and spells...
Concept:
Variant Human
Battlemaster Fighter/War Domain Cleric
Maul
That is my core concept. I feel it works well thematically and has a enough synergy to get by in combat.
Builds:
I've come up with a number of possible builds and am open to others as long as we stick to my core concept...