It depends on what you want out of your game.

Despite the many complaints A quite liked ETW with the right mods. I had a hard time getting into the gunpowder tactics but now I really really enjoy them. Definitely worth considering for the different kind of fighting style, the age of sail battles and the sheer scale of the map.

I didn't play Napoleon but from what I gather it's a somewhat polished version of ETW but on a much smaller scale.

Shogun II can be considered back to the roots of the series. A great game.