I have tried both OpenHAB and HomeAssistant extensively.

My recommendation: use HomeAssistant, do not bother with OpenHAB

Rationale:

    . OpenHab is very powerful but requires the user to invest a lot of time to configure it properly
    
    . OpenHab data model is very, very (and in my opinion unnecessarily) convoluted and it takes a lots of work/time to wrap your head around it

    . OpenHab is implemented in Java and drags along with it all the heaviness/unwieldiness of the Java world. In particular, if you want to do anything a little complex, that implies writing a Java plugin.

    . Home Assistant is Python. For simple, code-based changes to the system, YMMV but I personally think that Java vs. Python ... Python wins hands down.

    . Home Assistant works "out of the box" for most things, and is also very flexible when you want to

    . The Home Assistant community is much larger, and if you are doing exotic stuff, you'll find a ton more support online