I'd like to know the names of all the districts in the manga, the name and appearance of the king and nobles and other important political figures in the human government. I'd also put some focus on the more experienced soldiers and veterans of the Scouting Legion and the Garrison. Seriously, they were getting killed in Trost ,the 57th expedition and the battle of Karanese, while the greenhorns of the 104th were doing the most relevant stuff and surviving (or so it seemed).

Lastly I'd like to see the other members of the 104th (especially those aside from the top 10 plus Ymir and Armin minus Annie and Marco who joined the scouting legion, but never got even as little as a honorable mention) do something.