* A single style specification format that works well for both base map rendering and data overlays
* Parity across native and web rendering
* Smooth SDF text rendering with decent i18n support
* A font to SDF renderer that is open source: https://github.com/mapbox/node-fontnik
* A tiled data format that is open source: https://github.com/mapbox/vector-tile-spec
I hope this licensing change can spur some competition among open source renderers. I’d recommend taking a look at:
* Tangram: https://github.com/tangrams/tangram - another WebGL based renderer with some key advantages over MapboxGL JS such as custom shaders and canvas text
* OpenLayers: https://openlayers.org has some vector and WebGL capabilities now as well
* Harp: https://www.harp.gl is another new WebGL option
I've been working recently with Tangram, so contact me (see user link) if you have questions or are interested in collaborating!