Well for me the worst part is the typography. It's something blurry and pixelated. Maybe using bitmaps with Textmesh Pro plugin for the street names can make a real difference.

Everyone has their own understanding of good quality.
You can adjust the quality:
Tileset - Width / Height (pixels).
Drawing to Texture - Size of texture.
Select values for the best quality/performance for you.

No, we do not plan to add vector maps.
Unity just does not suitable for this.
Make it on flash or html canvas easy.
Make it on Unity is incredibly difficult and slow.

Can you give me good quality settings to render the tiles? Im aiming desktop app.

Do you have any plans to work with vector maps in the future?

I could make the image clearer!
Thank you for great help!

Reduce Width / Height (pixels) for tileset, or the size of the texture for the other controls.
Or increase «text-size» in MapBox Studio Classic.

Because of your advice, It worked fine with Custom-Provider and a valid URL of Mapbox.
Thank you.

I will draw a tilted large map, so I want renderings with a little higher resolution.
I know that map providers provide only small textures.
It is okay that labels are too small to read because I won't show them.
So it seems like there are any solutions...

I would be glad if you tell me implemented features, actual cases or helpful ideas.
Thank you once again.

MapBox not in the description, because you can not select it in the list of providers.
You need to use «Provider - Custom».
In the documentation has a section on using of MapBox.
Online Maps supports all maps that have WGS 84 projection and bitmap tiles 256x256 pixels. This is most of the maps.

By the way, Mapbox isn't included in supports of map providers in AssetStore's description.
Do you have any reason?

For your requirements, I recommend using MapBox Studio Classic.
https://www.mapbox.com/mapbox-studio-classic/
This is a great program that can make almost any style of map.

Important: MapBox Studio Classic can make bitmap and vector maps. Online Maps can work only with bitmap maps.

I want information about custom styled maps.
Which map providers provide custom styled map?
I want to compare them.

In particular, I want to select colors of water, lands and roads.
At same time, I want to hide all texts in textures.
And I will publish applications for business.

I think that almost textures contain displays of their copyrights or logos.
I don't want to show them in textures.
And I will show them in another space if necessary.
Is it possible within their terms of use?

Which provider do you recommend to meet these requirements?
I hope that I can hear your recommendation.

Thank you.