I just watched the first episode of B5. It was good, which actually didn't help me make my decision
I enjoyed the characters, and the story was pretty good. I want to see where it goes from there, and learn more about the universe.
Before, I was leaning towards Farscape. Now, I don't know which one I want to see more. Having a ST feel is cool, but its not a deciding factor. Farscape has a lot going for it, as well. I guess I'll just have to keep thinking about it. I'll definately be getting both eventually.