There was a court case over this. The court found that it wasn’t true that DS9 was based on Stryczynski’s pitch.
I was at a con in the early 90s shortly after DS9 had its first season. Rick Sternbach came out. He did an entire slide show of all the production design evidence they’d submitted to the court. They’d working on developing models for a space station for a show for a long time before. He had huge numbers of drawings. The big thing was the decision to switch from a Federation built mushroom shaped station to an alien design.
I finally suffered through the first 4 seasons of Babylon 5 this year. While there are good moments, the production values, writing, and acting are just not on a level with DS9. It felt like watching a big 3 network soap opera in space a lot of the time, with that same type of acting style. A couple of characters were great, but that's it. DS9 was just a better made show all around. Babylon 5 proves that you can have great ideas, but if the entire production situation doesn't come together in an equally high quality way, you aren't going to get an equally good result that will hold up over time the same way.