Honestly g'kar and Londo are the only two exceptional characters in the franchise, everyone else is meh. By contrast I'd say most of the ds9 main characters are solidly good, well written, great arcs, well acted. Odo, kira, and quark and nog are exceptional to actors telling exceptional stories. (I love sisko but sometimes Avery Brooks overacts) Why is it always the aliens?
On rewatch b5 was definitely better than I remember it being, but it doesn't have episodes that straight up make me cry. DS9 has me crying from episode 1.
Some episodes of DS9 were truly joyous to watch because the actors you mention were clearly having so much fun with the roles. Adding to them; Gul Dukat, Damar, Worf, Weyoun, it was just so great.
Babylon 5 is similar in that a lot of the scenes featuring Lando or G'kar were just mesmerizing. Garibaldi's hard boiled detective persona was a treat too.
I agree that G’Kar and Londo are exceptional characters, but I would take Vir Cotto over a dozen Nogs and Quarks any day of the week. And I rate Neroon over Odo too. Granted Neroon didn’t get much screen time as Odo, but he has the same kind of arc and carries it off much more convincingly. Kira is a pretty great character too, in most episodes.
I've always loved Vir's character. His ... optimism in the face of all that he sees. How hard he tries to be good, and to be the moral compass for those around him. And then the little wave to Morden on the pike. What a wonder, moon-faced assassin of joy he is.
I dunno. Maybe Andreas Katsulas acted the heck out of it, but I don't remember G'Kar ever getting lines/episodes like The Wire ("Especially the lies") or In The Pale Moonlight.
That being said, the cast isn't quite as charasmatic as the best of DS9, but surpassing Garak is a tall order.