I liked B5, but for me the poor special effects took me right out of the story in a lot of places. I think DS9 did a much better job helping me suspend my disbelief in that area. Also the gratuitous mystic philosophy of B5 turned me off a bit. However, the stories were just as epic as what we saw on DS9, and B5 played things less safe than DS9 did - which was a point in its favour.
I never understood this knock on B5s SFX, they were the prime fillet of CGI of their time. S1 was a bit rough, but... Maybe it's the "Cartoony" aspect of the CGI (I personally enjoyed that part of the SFX, it made things seem more alien). As far as Gratuitous Mystic Philosophy, I have to point at the Profits in DS9 and ask how B5 was more gratuitous? At any rate, like I said, I do adore both shows.