[jdance]

For complex GIS stuff in OpenLayers, you can do stuff like connect to a GeoServer instance and edit features with a ready made protocol like WFS-T. I have been involved in making these kind of tools for enterprises, like editing address points and routing paths in the browser, with transactions and edit sets and things like that.

When I was working with this stuff, Leaflet was more "view only" and not so much editing. This was back in the "have to support IE6" days. I remember trying Leaflet for a simple project, but gave up since I could not set a bounding box for panning (the map was only supposed to show a limited area of the world), while OpenLayers seemed had every API feature one could wish. Although more bloated, less polished :)