OpenStreetMap example looks superior but I think it didn't get enough research for this article.
Anyone can use Leaflet together with OpenStreetMap for free* for heavy commercial purposes[0] if you make your own mirror/render of OSM tiles. Also simple reverse proxy cache[1] can keep public servers usage acceptable. Styles can be also modified at render stage, e.g. [2].
*The cost is only your one time setup work and then any monthly hosting bill.
I encourage anyone to prefer these open alternatives and of course donate money, time or hosting to help develop them.
[0] https://help.openstreetmap.org/questions/4669/can-i-use-open...