What feat/ASI should I take?

[CheddarChampion]

I am playing a Conquest Paladin 8/Zealot Barbarian 3.
My plan is to become Conquest 13/Zealot 3/Lore Bard 4.
Stats of 18/14/14/11/11/19. Scourge Aasimar, GWM, Resilient: Constitution. (Rolled stats + long story why I'm not a V. Human anymore.)

I plan on taking "Menacing" at Bard 4 but I'm unsure what to take at Paladin 12.
I see my best options as Str+2, Int+1 & Wis+1, Mounted Combatant, Mage Slayer, Inspiring Leader, or Sentinel.
All of these are in line with my character's personality.
What would you recommend I pick up?

Spoiler: More Info

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I currently have a Mace of Disruption (but with the stats of a halberd, flavored as a Dire Flail), a Ring of Free Action, a Periapt of Wound Closure, and a Hat of Disguise (in bracelet form).
We are using Strongholds and Followers and the Magic Item buying rules from XGtE. I have a level 1 temple. I plan to buy a Fochlucan Bandore and maybe Mithral half-plate.
Allies are Abjuration Wizard, Kensei/Horizon Walker, Beast Master, Heroism Paladin, Battlesmith, Divine Soul/Hexblade/Fighter.

[Quoz]

Get Charisma up to 20, whether with a half feat or as part of an ASI. A conquest paladin is all about that fear aura, anything that pushes it higher is solid gold. The fact that it also boosts all saves for you and anyone in the front line with you is also a very nice plus.

[CTurbo]

I would take Menacing and +2 Str in that order with the next two possible ASIs

[Expected]

I am playing a Conquest Paladin 8/Zealot Barbarian 3.
My plan is to become Conquest 13/Zealot 3/Lore Bard 4.
Stats of 18/14/14/11/11/19. Scourge Aasimar, GWM, Resilient: Constitution. (Rolled stats + long story why I'm not a V. Human anymore.)

I plan on taking "Menacing" at Bard 4 but I'm unsure what to take at Paladin 12.
I see my best options as Str+2, Int+1 & Wis+1, Mounted Combatant, Mage Slayer, Inspiring Leader, or Sentinel.
All of these are in line with my character's personality.
What would you recommend I pick up?

Spoiler: More Info

Show

I currently have a Mace of Disruption (but with the stats of a halberd, flavored as a Dire Flail), a Ring of Free Action, a Periapt of Wound Closure, and a Hat of Disguise (in bracelet form).
We are using Strongholds and Followers and the Magic Item buying rules from XGtE. I have a level 1 temple. I plan to buy a Fochlucan Bandore and maybe Mithral half-plate.
Allies are Abjuration Wizard, Kensei/Horizon Walker, Beast Master, Heroism Paladin, Battlesmith, Divine Soul/Hexblade/Fighter.

If you are not adamant on Menacing, I'd take an ASI for +1 Wis and +1 Cha. Then take another feat. Maybe pick up a shield and take Shield Master for the BA shove?

[KillingTime]

Wis +1 / Cha +1
Bumping two key stats is so much bang for your buck, especially when it means you're maxing out Cha.