I really love all the cast apart from Talia Winters who is pretty dull. I think Michael O'Hare as Sinclair gave one of the definitive sci-fi leading man performances, though many dislike his old fashioned style of acting. I'd definitely recommend you stick with the show. Londo Mollari's arc is among the most powerful drama you'll see on screen. Him and G'Kar are ultimately the reason I'd pick B5 over any Trek.