Star Trek looked much better. They couldn’t do the numbers that B5 could do, at least not until the later parts of DS9. But what they were able to show actually looked realistic. B5’s effects were very, very clearly done on consumer-level computers. They were quite good considering, but didn’t look real. Star Trek was doing things with large physical models and it showed. Ships and stations looked like real objects (since they were!) rather than the smooth curves of everything in B5.
As a young SF devourer at the time, the cheap effects were a major turnoff and one reason I never got into B5.
Star Trek at the time had better effects (including DS9, even though I prefer B5!).
The trick with effects is to make whatever you have look good. There are a few ways of doing that. 2001's effects are genius and still look pretty good nearly sixty years later. They look better than 2010's from the 1980s. In fact, I'm even impressed with Forbidden Planet — yes, there are a lot of painted backgrounds but it does very well with what it has.
As a young SF devourer at the time, the cheap effects were a major turnoff and one reason I never got into B5.