Well, my favorite 2013 map mod has finally been converted to FS 2015
It's called Wildbacktal (wild creek valley), and it's a very nice sized map set in German mountainous terrain.
The fields you start with are small, irregular shaped and far from level, even steep at times, so the map is very suitable for singleplay as you won't be spending hours on just harvesting one huge field.
A lot of roads are narrow, and there are large elevation changes, making this a very fun and challenging map where you'll find yourself saving your small equipment as the large stuff doesn't fit on some of the fields, and certainly not on your starter fields. You'll find short routes to your farm to be pretty steep, so if you lack the horsepower you'll have to take the long way around.
Next to that the map has an abundance of forest, and driving to further away delivery points is a joy as the valley is very scenic.
Anyway, download here:
http://www.modhoster.de/mods/wildbach-tal--8 Sorry, very slow download link, but it's worth it.
You'll also need the map trigger mod or you won't be able to open the doors on your old school farm building:
http://vertexdezign.net/downloads/animationmaptrigger
The farm has an old fashioned attic storage, and you can retrieve your harvest through retractable chutes. To see where everything is on the map check the self explainatory pics on the download site. Any additional supported mods are listed at the map download page, but are not mandatory. Enjoy!