I have recently come across Mapbox Studio, a handy online tool for designing maps. It's described as 'Photoshop for maps' as it lets you control a lot of map's design features. 

You can control the map's colours, fonts, 3D features and camera angles. You can add your own fonts, icons, and textures to fit seamlessly with your brand. You can tweak the map in the default style or create one from scratch using custom data and style layers. The online platform also includes a dataset editor that allows you to manage your own datasets. You are able to add point, line, and polygon features with draw tools as well as add custom fields.

Once published the maps can be easily integrated into your app or a website via Mapbox’s SDKs and APIs. It’s also possible to download your stylesheet to embed directly in your app’s source code. Finally, it’s possible to export high resolution images of your style for print.

It's certainly worth a good look.