I have finished Babylon 5.
I find it bizzare that Sheridan doesn't seem to have made more close friends during the 20 years after the show takes place. At the end he only summons a half dozen people from his stint on Babylon 5. Also feels conspicuous that all of them survived the 20 years. Even in TNG's future epilogue All Good Things you had at least one person who didn't make it (Troi).
The show was overall good. It wasn't the masterpiece it's fandom hyped it up to be, but it was enjoyable. It did stand out to me that they kept phrasing stuff in Judeo-Christian terms. "The darkness and the light" and "we answer to a higher court" (what court?) or "faith prevails" (faith in what?) and so on, but it feels vapid since the show doesn't believe in any one true God or is grounded in Christianic morality. This isn't a problem specific to Babylon 5 specifically: lots of fantasy that riffs the aesthetic of LotR's grand epic struggle but leave behind the underlying beliefs suffer from this.
The show didn't overstay its welcome. I can only think of one episode that I skipped. Can't think of any particularly unenjoyable episodes. DS9 ran for 7 seasons and there are many episodes I just don't find enjoyable and skip whenever I rewatch that show.
I think one issue with the show is that you have to question who you are rooting for. In Star Trek, you are rooting for the Federation. When the Klingons or the Romulans or the Borg are threatening the Federation, you want the Federation to be protected. You want to see what happens next. In B5, the Earth Alliance is never likeable so it's hard to care about any threats to it. Every representative from there is an asshole. Almost every other race - Minbari, Centauri, and Narn - seem to be more likeable, but you don't really see what life is like on their homeworlds, only see one or two characters from them on the station. So once the show ends and you find out that there is a novel about the Psi Corp, you have to wonder "why care what happens to the Earth Alliance?" Or a hypothetical sequel series following David. "Why care what happens to this setting?".
I guess the only other thing to comment on is the production values and aesthetics. The big bulky Vorlon costume really spruced up the look of the aliens, but sadly after Kosh and his replacement were gone from the show, you're just left with a bunch of humans and humands with rubberheads. Not that I dislike rubber-forehead aliens but its kinda samey. Star Trek made the setting prettier with Robert Stromberg's gorgeous matt paintings of cities on Bajor and Cardassia and Ferenginar, and I liked the physical model spaceships more. The CGI locations and spaceships of Babylon 5 don't look bad but they're just not appealing to look at. Also, the music tended to be overall forgettable for me. The only track I can remember is that remix of the main theme during the first season.