Iron: hassle to get, only useful early game
gold: It looks cool?
Diamond: Is debatablely more dangerous to obtain than netherite with the cave update even with strip mining
Netherite: The superior armor with no downside, which is very sad since diamond was the most iconic thing in the game next to creepers. Having this armor slow you down slightly would be great. And netherite is not hard to get at all contrary to the hype surrounding it, it's lame to wear, looks horrendous, is just better than everything which is lazy and seems like an mccreator mod ported into the game but with a Mojang gloss added. But it's still the objective best armor in the game despite my qualms with it. Here's to hoping an end update brings something unique with enderite or something.