I found Full +2 before Mythril and iirc you can buy Fulls from the vendor. Which is moot unless there’s Armor like Chain of Comradery with other bonuses which is the main thing (after Weapon Training) motivating me to look at Fighter. Likewise if there’s a good Tower since Fighter is only class with Tower Prof.
There is one niche I can think of where I’d want to look at Mut Warrior: Effortless Dual Wielding best available one-handers *without Shatter* to hit Mind Immune bosses, using the three Feats saved on a good CM or as you suggested Vital Strike with Two-hander (preferably Glaive/Bardiche) and the Cleaves for non-bosses. That’s where you’d really need all that AB.
With Shatter it’s probably going to have the highest CMB available so if you can manage the speed issues you could Move + CM bosses if you can offset the INT malus.
There's only one highly rated tower shield I've found. It's a +4, evil only that gives an additional -2 to hit vs evil. Think I'll probably give that one a miss.
I'm still definitely more likely to include a barbarian (particularly a Mad Dog), a paladin, a bloodrider, or a cavalier than I am any variety fighter. Cavalry are just faster, better able to readjust position to attack, and better protected than foot sloggers.