Europa Barbarorum.
This. Most accomplished historical mod for any game, only thing that supersedes the AD1257 module for WB in terms of level of research that has gone into it. Great balance and atmosphere, too.
Other than that I think Medieval I was the the height of the Total War series (where the new Shogun dlc 'yanks vs samurais' must be the absolute low point in regards to theme and fantasy elements), but Rome was quite good, if more arcadey than the previous games.