Mapbox has some beautiful maps. I love the terrain and pretty everything you can customize with them.
I don't agree on the clustering of pins on the map that they have in their example thou. Clustering is great when your are way zoooomed out. In this case it's just confusing. I press a cluster marked with a "2": Four pins pop up. I see this a lot in map services that uses clustering. I want a lot of pins on my map when searching for real estate - I want to get a sense of the market.