I always play with these mods:
Bluehawk's Russian Expansion Minimod - https://forums.taleworlds.com/index.php?topic=349194.0 - Adds new Russian infantry and cavalry types, in addition to slight improvements to weaponry and existing items.
Bluehawk's Fixed Scabbards Minimod - https://forums.taleworlds.com/index.php?topic=350972.0 - Adds scabards to swords without them.
The Bowman's Improved ans Fixed Siege Scenes - https://forums.taleworlds.com/index.php/topic,343274.0.html Improves the AI on siege maps and adds a few more improvements to them.
I occasionally play with these mods:
Kagestorn's Grenadiers à Cheval de la Garde Impériale - https://forums.taleworlds.com/index.php/topic,340549.0.html - Adds French Imperial Guard Horse Grenadiers to the game.
Wolsten's Brunswicker Troops Minimod - https://forums.taleworlds.com/index.php/topic,363809.0.html - Adds units and uniforms surrounding the Black Brunswickers, in addition to making them proper troops.
Wolsten's 44th East Essex Minimod - https://forums.taleworlds.com/index.php/topic,363571.0.html - Retextures the British infantry to make them resemble the 44th Regiment of Foot.