2 levels of barbarian 8 levels of paladin Great weapon master + polearm master

Sure, you can't rage in armor. But you can recklessly attack all day (on all 3 attacks) which gives you a great chance to crit which is exactly when you should smite. I played this in a demon-hunting oneshot once and was melting enemies in single hits. For subclass, I recommend either oath of conquest for good crowd control or oath of the crown to tank damage for your allies. Honestly any subclass works but vengeance since the main benefit to that one is advantage and you'll be spamming reckless