Rome 1, Shogun 1, Med 1+2 - Visually they are old, AI is not great, many generic factions, rebels...but if you are into modding and like big overhaul mods. Especially Med 2 offers quite good mods, it was possible to edit campaign map. But there are still issues that no mod can fix and honestly if you are not into old games, they won´t satisfy you probably.
New stuff: Empire, Napoleon - Before Empire I would bet that TW with fire arms cannot be made. Empire offers large campaign map, many factions, added naval combat which for some is hard but some it. I will say one example, as Britain you can start focusing on dominance in Carrabean (navy, pirates) or North America (indians, colonies) or start with Europe wars..(taking Gibraltar, land wars with France,Spain...) or even star with expedition into India (melee native troops and elephants
)...Empire is offering special theatres for exotic resources, accesible only with fleets. In all other games fleets are operating around coast, Empire is only game with deep water/ocean naval warfare. Except lower FPS in sieges there are no major bugs contrary to popular belief. Napoleon is on smaller scale, with some improvements in many aspects. However on other hand, scale is limited just to EU, every campaign is very same.