I've actually been mulling over this question of AC for a wizard grappler (minotaur artificer). A level of fighter or cleric gives great armor that allows for a lesser dexterity, but he needed Expertise to be better for grappling. I am thinking I will instead have him grab a level of Rogue and take Moderately Armored. With 14 Dex, that gives him an AC of 18 or 19 before any magic items (and as an artificer, he could himself get that up to 23 for a heavy cost).