>>716917I have two recommendation charts from /a/ that feature unpopular anime picks from a group of Anons that enjoy watching anime that fly under the radar every season. If you're looking for original screenplay anime similar to Girls und Panzer, then these charts are a great place to start.
Here is my list of recommended original screenplay anime:
https://pastebin.com/EJk8fDkCI have completed all of these and I can assure you that most of them have satisfactory conclusions. My only criteria for selecting them was my own enjoyment, so it may differ from your own. If you have any questions about them, shoot me a reply as I will be leaving the tab open.