I’m trying to understand which GIS platform should I use for a new web application: leaflet or cesium.
Most of the data: 2d layers (gdb, PostGIS). Any thought? pros & cons?
Does cesium support ArcGIS server rest API?
It depends on what you need now, and where you’re going in the future. If everything is 2D and always will be, using leaflet might be more straight forward as there are a few challenges of 2D items on a 3D globe (all fixable, but some challenges apply because of the ellipsis of the globe). But if you want to mix 2D and 3D, it’s a no-brainer. Also, look at NationalMap for a mainly 2D environment using Cesium, and yes, Cesium has excellent support for all sorts of mapping interfaces including ArcGIS (plus the added Cesium Ion framework / platform you can use for all sorts of things).
Leaflet and 2D is a lot simpler, though as you only need to take X and Y into consideration (and z-indexes), but Cesium is a lot more powerful and fun, for what it’s worth. I’d look up Cesium Sandcastles for examples of all sorts of things you can do, and see if that’s what you needed. The documentation in Leaflet is better for simple examples of the API, while Cesium’s API is more extensive but with less detailed examples (so you may need to poke around a play more to do what you want).
And finally if you know, in your heart of hearts that there will never be any use of 3D in your app, then yeah, Leaflet is probably the way (even if it does have a 2D view, which you might also explore before making a decision).