When I was evaluating both projects about 5 years ago, I went with openHAB because they had native apps with native controls (and thus nicer design imo). At the time, HA was still deep in YML config files and needed validation before saving etc etc. Not great UX.
Nowadays, HA has more of the features I would want and other external projects exist to create your own dashboards that take advantage of native controls.
Today I’m using Homey because I’m still a sucker for design and UX after a long day of coding boring admin panels in the day job, but I think in another few years when the hardware starts to show its age that I will move to home assistant. Hell, there exists an integration to bring HA devices into Homey but that would require running two hubs and potentially duplicating functionality. We shall see.