1. Turks: Nothing like a faction closest to Mongols And Timurids. Oh and Janissaries and Sipahis rock. I even modded some Turkish uniforms and added some new units to make my new campaign better.

2. HRE: Not so much for their tech tree than their german attitude. Honestly, they have plainest tech tree of any Europeans but those crazy speeches are great and worth a listen.

3. None...I only played 2 campaigns....