[twelvechairs]

From my perspective at least theres a few main sides. From least to most ESRI-dominant:

- Web - ESRI never had a major horse in this race. Google Maps is still there but more common now is Leaflet and Cesium for 3D is basically the only option. Both Leaflet and Cesium are FOSS.

- Server - As you say postGIS is now the industry standard

- Programming - There's some people using ArcPy if you are in the ESRI ecosystem but the plethora of FOSS libraries out there are probably bigger in scope and fit together better than ESRI. PyQGIS is another option but in my experience not as heavily used as other open source libraries (all of which are based on GDAL, OGC standards and the Java Topology Suite)

- Desktop analysis - This is ESRI's core stranglehold and I think qGIS is now a competitive option for most users (certainly it has most of the core functionality) however there's a lot of inertia to move from big companies especially those that want ongoing external support/training.