I just saw B5 on hulu. I'll definately check out an episode or two to help make my choice.
I loved DS9, its probably my favorite ST series (although I might rank TNG higher just because i've been able to watch more episodes of it). I think that, with my tastes in sci-fi, I'll like both Farscape and B5. Right now I'm leaning toward farscape, but not enough to make a decision yet.