In that specific example, I'd rather just play Europa Barbarorum with its much more historical and realistic focus on units. However, I do vastly prefer real time games (generally more tactical than strategy since RTS games are generally so focused on the meta game and having a high APM clickfest you can't really sit back and enjoy the combat) that have varied factions. Actually now that I think about it the basic gameplay is largely the same for every faction in Total War mods and Sword of the Stars, but there are still quite a few differences that make certain factions stand apart and I like that, a lot.