When compared to the other two major OSS libraries I would say:
- Leaflet. Widely known, suitable for mostly simple use cases.
- Mapbox GL JS. State of the art library based on WebGL. Mapbox started off with a fork/extension of Leaflet called Mapbox.js but over time has moved on and created the Mapbox GL JS library from the ground up. Very fast, but requires a GPU due to WebGL.
- OpenLayers. Often used by more professional users. Probably the most features complete library. Also usable without a GPU.
- Leaflet. Widely known, suitable for mostly simple use cases.
- Mapbox GL JS. State of the art library based on WebGL. Mapbox started off with a fork/extension of Leaflet called Mapbox.js but over time has moved on and created the Mapbox GL JS library from the ground up. Very fast, but requires a GPU due to WebGL.
- OpenLayers. Often used by more professional users. Probably the most features complete library. Also usable without a GPU.