If, in game, you alter these differentiating factors by making armor that should be heavy, light (as in Baldur’s Gate games for instance), then the discriminating reason for choosing an armor instead of another ceases to exist, and it only becomes a matter of “which is more useful”.
So, if a plate armor protects me better, but is also light to wear, I’ll simply use that and that will be it. If my speed is not hindered, if my rate of attack is the same, etc etc, but I get better protection, I’ll obviously use the armor that gives me better protection.
BUT if this better protection comes at a cost (my movements are slow, both in walking speed and attack speed, I need to have a minimum strength requirement, etc), then I might choose to settle for the lower tier armor, which protects me less, but allows me to run, attack at my full capacity, allows me to carry more stuff in inventory because of the lesser weight, etc.
So, as I was saying, “better” amor needs to have a downside if you want armor to have an impact on gameplay. After all, full plate armor was rarely used, because it’s heavy as fuck and because you become tired fast and are a much slower, and therefore easier, target to hit. I do realize that this is a fantasy world, and people wear full plate armor even when they go to sleep, but that’s precisely the point that needs to change to make armors meaningful and not just an upgrade with no drawbacks.