Helldritch
Hero
The TWF bonus action is a bit meh... Most people prefer their paladins either with a shield or a two handed weapon. PAM let you use your bonus action for an additional attack. That is good. But shield masters helps you out with dexterity save, a bane for the paladin, it also means that now the Shield Master takes only half damage from dex base attack that allow a save and can now shove an enemy to allow for advantage on the prone opponent. An attack is nice, but the option of shield mastery is superior because of the flexibility it allows. Not only can the paladin do his attack(s) with advantage (if the shove succeeds) but his allies too.
This also have the benefit of letting the paladin take either the defensive style (for +1 to AC) which makes him get a potential 21 AC when he can get his hands on a plate armor. Or Duelist for a bonus to damage (which is nice, but a fighter is better with this bonus than a paladin. But that is an other debate...). More over, the paladin can always use his shield as an improvised weapon to make an attack with his shield anyways. It would be less efficient than TWF but it is an option still.
This also have the benefit of letting the paladin take either the defensive style (for +1 to AC) which makes him get a potential 21 AC when he can get his hands on a plate armor. Or Duelist for a bonus to damage (which is nice, but a fighter is better with this bonus than a paladin. But that is an other debate...). More over, the paladin can always use his shield as an improvised weapon to make an attack with his shield anyways. It would be less efficient than TWF but it is an option still.