I appreciate the feedback on the bladesinger/swashbuckler suggestions. Swashbucklers gain some benefit from CHA, but I would consider keeping it low as the big benefit is for initiative and Panache. It would be sacrificing the Panache disadvantage from single target in combat for the bladesong and shield AC, but point taken. Trying to optimize AC while still being a melee threat has largely been the goal with some RP flavor and combat style preferences being minor restrictions.
As an alternative, I was looking up how to get the highest AC and found that a Ranger 7/Wizard 1/Cleric 1 is the lowest level to be able to achieve a resting AC of 27 (given +3 shield and +3 half-plate), a magical item enhanced AC of 31, a combat buffed AC of 35, and a highly-situational maximum of 49. This is dependent on a the Medium Armor Master feat and Dex of 16, and the defense fighting style.
Source:
https://rpg.stackexchange.com/questions/67197/what-is-the-highest-possible-ac
Precluding the magical items as they are based on how generous the DM is, that gives you an resting AC of 21 and a situational AC of 30 without 3/4 cover, that is attainable at level 9 with Ranger 7/Wizard 1/Cleric 1.
I would like to propose that you can get a "more annoying" character with a bladesinger. By changing the feat from Medium Armor Master to Dual Wielder and using the standard array and no enhanced or magical items, you could achieve a situational AC of 31 by level 11, maxing out at 34 by level 20 without 3/4 cover. (probably sooner if you kept cleric as in the source post)
I suggest that Ranger 7/Wizard 2/Paladin 2 is a more practical and likely much "more annoying" build. This build precludes a shield (+2 AC) and the Medium Armor Master feat (+1 AC) and replaces it with the Dual Wielder feat (+1 AC) and Bladesong (+INT mod AC). The change from half-plate to studded leather comes at the cost of 3 AC, but no longer caps the DEX bonus to +2 which recovers 1 AC at level 1 and the remainder by level 11. (This depends on the DM allowing a variant human bladesinger. Without which, all following ACs are reduced by 1, which while not optimal, are still really solid)
A variant human bladesinging hunter paladin, wearing studded leather and dual wielding would have a favored enemy, colossus slayer, two weapon fighting, an extra attack and divine smite to be a serious threat while having studded leather (12 AC) + DEX mod (4) + Dual Wielder (1) + Defense fighting style (1) for a resting AC of 18. Add to that bladesong (only a +2 to AC until level 16), shield of faith and a shield spell (two bonus actions and a reaction) and you have an additional 9 AC, totaling 26 at level 9.
You would gain multiattack defense at level 11 for a situational boost of +4 AC against a creature after you've already been hit by them. You would max out DEX at level 12, giving you a +1 bump to resting AC and get to INT 16/18 at level 16/20 to bump the bladesong bonus to +3/+4.
As far as spells, you would be very limited on selection, but you would have 2 levels as a full caster and the rest as a half caster, which should give you plenty of fuel for shield, divine smite, and shield of faith.
This build is all kinds of MAD, requiring DEX and INT as high as possible, STR and CHA at 13 or more for multiclassing, and pushing WIS to -1 and keeping CON at 0 (hopefully you'd never get hit, but at least you get Evasion at... level 19). This could be reduced by choosing war cleric (WIS) over paladin (STR and CHA), but at the cost of divine smite. Depending on ranger spell selection, this may be a better way to go, but I would anticipate Divine Smite providing a lot more damage than ranger spells.
I feel like I'm missing something, so please set me straight if I did.
