These arguments are always fucking stupid because they never define what a knight or samurai is, and bring up retarded examples ranging from conquistadors to crusaders.

Lets at least set some ground rules: Both are from the year 1500 and wealthy enough to afford whatever armour they want in good quality. The knight has a halberd, the samurai has a naginata, as backup they have traditional swords of equal length and reinforced anti armour daggers. They are in a duel on foot on flat ground and temperature isn't an issue.

Now, under these conditions, I personally think the knight would win, the armour advantage is just too significant. I will say however it definitely wouldnt be a cakewalk like some people here think, people seriously underestimate samurai armour. It wasnt as good as western armour but it was very effective, and the fight would quickly devolve into a brawl. These larper guys have good unchoreographed videos where they put on full armour(reproduction armour thats less durable than real armour was, keep that in mind) and absolutely beat the shit out of each other to show what armoured combat was really like. They actually have a couple of videos with this theme
https://www.youtube.com/shorts/gRhNg9S4RzI