^^what he said is pretty well rounded unit strategy. Archers and light units have taken a buff though since my first time through, while horse and heavy have been strengthened. Still I have built very very few horse or heavy melee barracks on any world during any age, I just never was a huge fan. They both have pretty severe limitations and the barracks usually take up quite a bit more room.
Realistically, after archers and some other units were buffed and AI was improved, Early Middle Ages Units (EMA) kinda stink in general. Actually, no, they always kind of sucked, lol. There will be a significant and noticeable difference in unit strength once you get to High Middle Ages (HMA). So basically, if you're going to wait till you're at the end of EMA tech, you might as well wait for the HMA tech.