Out of above suggestions, one I like most ( apart from my own suggestion, of course ) would be modified "reduce enemy AC" in a way to prevent making game easier. And that would require "increase enemy HP" proportionally to reducing enemy AC. That way, enemy would remain roughly same challenge but with less misses. Other suggestions are hard to balance to keep challenge and still reduce misses.
But even modified "reduce AC, increase HP" would still leave other issue - DnD is currently balanced around AC. Reducing AC would reduce significance of proficiency with weapons, and even significance of your main attribute like STR/DEX since increasing them help with Ability Modifier used in Attack Roll against AC. In other words, currently increasing STR/DEX helps you twice with your damage: first, increasing chance to hit and, second, increasing weapon damage. If they reduce AC on enemies, increasing your STR/DEX would be less impactful.
If you reduce AC and increase HP (as Larian already did, because they thought that you miss to much with normal 5e rules, too), you will also have to deal with the effect of increased HP on spells, i.e. they also need to do more damage, or a fireball is just laughable, because an enemy just loses like 5% of its HP.
And there is also the same matter with saving throws. Why should I use a spell that does only a relatively small amount of damage (compared to full HP), and cost me a spell slot, and maybe does only half damage? The risk - reward system is not in balance anymore with melee, were I always hit, but do not much damage.
This proposal devalues Spell Slots too. Not just STR/DEX and Proficiency Modifier (for your to hit chance).
ANd regarding the sliders, even with a 95% hit chance, over the length of the game I will probably see it a couple times, that my fighter misses four times in a row. And rest assured, with higher levels, magic items, spells, it's actually quite easy to achieve 95% hit-chance, or even 99.75 hit chance (when you have advantage).
And in the end, it also comes down to personal taste. Maybe my barbarian misses sometimes, but then are these spectacular critical hits, that kill many monsters with 1 hit. And if I have a to-hit chance of more than 80% is really good in my department. But this may also be because I play PnP Table Top games since I am 12 years old.
