leaflet and open layers have different use-cases.

This is a massive oversimplification, but roughly, one way of thinking of it is that leaflet is more suited to consumer-facing web maps and openlayers is more appropriate for heavy gis workloads; e.g. a web app for visualising business locations worldwide vs a web app for manipulating SHP data and EPSG projections.

That's not to say Leaflet can't be used for the latter -- e.g. in combination with some other tools like turf -- but OL is being developed with this kind of stuff on mind.

openlayers has more functionality built-in. in leaflet, things like editing geo-features are in plugins.

OpenLayers vs. Leaflet is a bit like Rails vs. Sinatra: one is a lot bigger and heavier, but you'll probably end up reimplementing 1/4 to 3/4 of its features if you go with the other.

Plenty of cases where either choice is the right one, IMO.

I use Leaflet for 90% of my mapping projects. But once in a while a complex requirement comes along and only OpenLayers has the power to solve it. Rotating a map was a recent one.