What is the best option between “half-plate armor+dexterity+Medium Armor Master feat” and “plate armor”

I want to make a melee fighter, and I’m strugling on the choise of my armor for the build. I put my stats on my character when I’ll define all I want to do for my build, so let’s suppose that I can have the stat and race you want to define which armor is better.

I hesitate between taking an half plate and a plate armor whenever I can (which will be replace with their magic version whenever I can, my DM allowing us to buy magic items with gold).

On one hand, Plate give the best base AC, 18, and have a strength and stealth restriction that force me to play only in one way, but have the advantage that the only cost on the character sheet to have some point in strength.

On the other hand, half-plate give 15+dex mod (max 2) AC, which is less and with the same stealth restriction, but with the Medium Armor Master feat I can have the same amount of armor, and I can play stealthy if I need to. Plus investing in dexterity seams to me a better choice regarding that dexterity have a far more usefull saving throw, far more skills affected, and give bonus on damage and attack rolls with some weapons.

On my point of view half-plate look far better, but on most of the online build that I found, they use Plate armor and not half-plate, so I think I miss something crucial.