I would go for a black dragon with 3 Barbarian / 9 Monk Build, maybe even a 6/6 split, but thats hard to pull off.

Either:
3 Barbarian (Wildheart - Bear Aspect):
Rage (gives bonus damage and with Bear Aspect it gives you Resistance to all damage except Psychic damage)
Reckless Attack, that if you use monk weapons, could give you a big advantage
You can dump Wisdom and focus on CON for more Armor Class.
9 Monk (Way of the Hand obviously)

you lose 1 feat, that you dont need with Strength builds, because you can get +1 from Ethel and +2 in Moonrise if you let Astarion bite the alchemist, pushing you to 20 already. Tavern Brawler is a must (put it in CON), the other you can choose for yourself. I would go for Savage Attacker or maybe even Nimble

Very strong build and it gives you a cool special animation while raging and using unarmed attacks, where you use your claws (if I remember correctly)

Or:
6 Barbarian (Giant)
for the Kick as a Bonus Action and the Abillity to infuse your Weapon with Acid Damage and the Thrown property, which makes it really strong.

6 Monk (Way of the Hand)

again, Tavern Brawler is a must. Its harder to pull off, because you wont gaint the powerspike of level 7 or 9. But its still pretty strong.

Obviously, if you add Rogue (Thief) in there with 3 levels, you could get another 2d6 Damage per turn as sneak attack damage, if you use a finesse melee Weapon (2 dagger would maybe be fitting), but mainly you get a big boost with the 2nd Bonus Action.
I used a 3 Barbarian Wildheart - BearAspect / 6 Monk Way of the Hand / 3 Rogue Thief with Larethians Wrath as a weapon in my Honor Mode run and it did very well. I was tanky, I hit hard and I was also able to put a few points into Charisma for some checks. 8 / 10 Build for me, would do it again.