my only problems with D&D's AC system is that it severely under-represents the defensive value of shields and makes parrying / blocking hits with a weapon into something rare, specific to certain builds.
If you are a standard 1 level mook and your chance to land a solid hit on another guy just like you is 50% and than someone hands that guy a large shield, in reality your chances to land another solid hit would down to like 10%.
Other than that, its great - I DM a game in pf1/3e right now and I keep a spread sheet for all the PCs and characters with tables for AC to part of the protection that blocked the strike. Saves me time coming up with descriptions of what happened - at a glance I can tell 'this bounced off your armor, this next one got deflected by your magic shield'
I also don't describe HP damage as this >>85520993>shoot somebody in the face 5 times
The point is, you actually don't shoot him 'in the face'. he just barely gets out of the way needing to flex so fast it hurts him... or your arrow gets stuck in his armor and is now tearing up his skin with every move as a non-debilitating but rather annoying wound... or it grazed him and bounced off..
Its on the 6th attempt that you actually shoot him in the face.
Same for falling - grabbing unto ledges, breaking his fall on every object between him and the ground and doing all kind of action-hero shit to survive that fall. Lucky that it got only got him superficial wounds.
One of my few rules at the table is 'if you guys try to exploit the system in a way where I can't come up with a plausible description on the spot, expect to die.'
Like you decided that your character leaps off a dragon at 200ft height in middle of a rocky deadlands? I can't think of a way your dude would live so fuck you, I am not even rolling fall damage, your guy just died. You get a badge 'i stumped the DM' - now roll up your next char.
That one rule does a lot of work to keep our games sane.