With 5E, the Paladin's fluff changed to be less reliant on a deity and more reliant on an oath. Conviction in said oath unlocks all kinds of supernatural powers for the Paladin; essentially, their Charisma -- their Force of Will -- enables them to create miracles, smite enemies of their oath, heal the sick, and so on.
But what if the Paladin embraced this generic oath idea more? An oath doesn't have to be divine magic, and the Paladins IRL aren't that far apart from the Knights of the Round. In this way, perhaps "Lay on Hands" could be turned into one of a few potential options the Paladin picks, and their choice of subclass has a greater impact on their spell list. A Paladin in service of a lich would essentially be a Death Knight, and have more necromancy spells; a Paladin in service to an Archmage is your more generic spellblade. The best part is that by giving Smite a customizable damage type, you could easily flex the Paladin's flavor any number of ways. And of course you can still have a Paladin who serves gods or whatever.
Anyway, this is just a little idea, not one I'm sure I'll pursue as I enjoy my own Pendragon class, but the Paladin-as-Magic Knight could potentially better address the many varied tastes D&D players are meant to have.