Polearm Proficiency to wield a Halherd, Glaive, or Pike. Take Polearm Master and Sentinel feats so you can smack anyone who runs up to you and stop them from getting into melee range.
Pretty gimmicky but kind of funny too. Works with Sorcerer and Warlock as well.
Alternatively, now every class a human plays is one feat away from medium armor and shield proficiency. You could go for a traditional wizard or sorcerer and be rocking 19AC with half plate and a shield.
Still, given Human Fighter is the most popular combo ever I hope Larian thinks of something better than this or else there's no reason to play a human fighter.
