OpenHAB has potential but you can also hit a wall pretty fast. It’s really good for some people.
I think if it was me and I was still in my coding days I would look more at something like HAM bridge. This was written by a community member here, and is a software-only option that you run on a Mac. Very powerful, very cool, and lets you leverage the SmartThings device controller capabilities while offloading the more complex logic.
But some people like building their own stuff from the ground up as well. So there are a lot of different directions you can take. 