Song of Shadows and Dust already have profiles for the roman period like gladiators, roman gangers, civilians, bodyguards and i think celts and germans (probably many more), Advanced Song of Blades and Heroes has profiles for fantasy (orcs, humans, elfs, hobbits, dwarfs, etc). Having said that probablly the easyest for you would be Song of Shadows and Dust.
Ravenfeast is a easy to learn set of rules for Dark Ages but with the advantage of change the profiles on a easy way for several periods plus you can add adicional rules for the chosen period so that you have a greater "feeling" of that said period. Sometimes the simple change of name is enough without changing anything else (instead of bondir viking call it germanic warrior and his characteristics are the same as well as the equipment).