From what I've seen, we have 3 Paladin subclasses: Ancients, Devotion, and Oathbreaker. Ancients and Devotion are very traditionally goodly-hero themed, but there's a third subclass in the PHB that doesn't seem to have made it in, and that's the Vengeance Paladin. The reaosn I'm pointing this out is because I think larian may have got the wrong idea of Paladins by creating conditions that your oath can be broken that apply to all Paladins, regardless of oath.
This is important because of the tenets that each oath follows. these tenets are part of your oath that you follow as a Paladin, but they aren't all goodly-hero stuff. The thing that makes an Oathbreaker an oathbreaker is that they literally have no oath, and no tenets, you make your own rules and set your own boundaries.
But whether or not you go against your oath shouldn't be some kind of universal metric, not all Paladins have tenets against deception, stealing, or even murder. Conquest Paladin arguably had tenets in favour of murdering, Glory Paladin is all about being the most glorious version of yourself that you can be, and Watchers Paladin only has tenets against being influenced by extra-planars (so accepting tadpole powers would immediately violate a Watchers Paladin's oath).
So lets look at the tenets:
Tenets of the Ancients
The tenets of the Oath of the Ancients have been preserved for uncounted centuries. This oath emphasizes the principles of good above any concerns of law or chaos. Its four central principles are simple.
Kindle the Light. Through your acts of mercy, kindness, and forgiveness, kindle the light of hope in the world, beating back despair.
Shelter the Light. Where there is good, beauty, love, and laughter in the world, stand against the wickedness that would swallow it. Where life flourishes, stand against the forces that would render it barren.
Preserve Your Own Light. Delight in song and laughter, in beauty and art. If you allow the light to die in your own heart, you can't preserve it in the world.
Be the Light. Be a glorious beacon for all who live in despair. Let the light of your joy and courage shine forth in all your deeds.
Tenets of Devotion
Though the exact words and strictures of the Oath of Devotion vary, paladins of this oath share these tenets.
Honesty. Don't lie or cheat. Let your word be your promise.
Courage. Never fear to act, though caution is wise.
Compassion. Aid others, protect the weak, and punish those who threaten them. Show mercy to your foes, but temper it with wisdom.
Honor. Treat others with fairness, and let your honorable deeds be an example to them. Do as much good as possible while causing the least amount of harm.
Duty. Be responsible for your actions and their consequences, protect those entrusted to your care, and obey those who have just authority over you.
And finally:
Tenets of Vengeance
The tenets of the Oath of Vengeance vary by paladin, but all the tenets revolve around punishing wrongdoers by any means necessary. Paladins who uphold these tenets are willing to sacrifice even their own righteousness to mete out justice upon those who do evil, so the paladins are often neutral or lawful neutral in alignment. The core principles of the tenets are brutally simple.
Fight the Greater Evil. Faced with a choice of fighting my sworn foes or combating a lesser evil, I choose the greater evil.
No Mercy for the Wicked. Ordinary foes might win my mercy, but my sworn enemies do not.
By Any Means Necessary. My qualms can't get in the way of exterminating my foes.
Restitution. If my foes wreak ruin on the world, it is because I failed to stop them. I must help those harmed by their misdeeds.
We can see that a Devotion or Ancients Paladin is definitely more on the goodly-hero side of things, lying, cheating, and stealing are forbidden by the tenets of Devotion, and while these acts are not specifically mentioned by the tenets of the Ancients, such things are probably not acts of mercy, kindness, and forgiveness (though that might be open to interpretation in some circumstances).
But even here, the lines are blurred. In the PfH we saw the cut scene with Lae'zel having been captured by the Tiefling hunters, and I noticed that they have put in a new Deception (Paladin) check to get the Tieflings to leave so you can free Lae'zel. That's a lie. You're still lying to them. But somehow this doesn't break your oath, but normal non-Paladin lies will? I don't like that. You wouldn't have to put in that allowance if you didn't universally punish Paladins for lying in the first place.
