It was a good show though it irks me that one of the major premises for the setting is that an advanced (later portrayed as wise) elder race just assumed some uncontacted aliens must have the exact same social norms they do and then initiated a genocide over a single incident with no further attempts at contact.

I ended up liking the Centauri simply because they're at least very relatable assholes who actually seem to appreciate alien cultures despite being an imperalistic society.

Eh, best is subjective, mine changes often and I like that. Top Five (or at least ten) probably for the vasty majority if they see it, writing, acting and production are outstanding, concept rocks. As our society has been influenced, Star Trek (especially TOS & TNG) has the high ground IMO, and maybe that's a good thing, hope is needed and B5 is not foremost that, it's a damn good story. If you like scifi TV and haven't seen it, do, no ifs or buts.

I happen to be doing a rewatch currently and I am reminded to recommend The Lurker's Guide to Babylon 5 as an accompaniment to your watch, it captures the 90's internet fan experience brilliantly.