War Without End Part 2 - If this future is unavoidable (and they say outright that it is), that sucks. Why set the future in stone? Now I know, whatever happens, that Londo and the centauri are screwed, and Sheridan can literally do nothing. Londo will just keep going until he becomes emperor, and a puppet of the shadows, then he'll be killed by G'Kar. Knowing how stuff like that means that there will be no more suspense with Londo.
You've known how Londo dies since the very first episode you saw. You've known that Londo would become Emperor for several episodes, too. Knowing what happens doesn't mean you know all there is to know. On B5, it's the journey that counts. And there's a lot more of Londo and G'kar's journey to see. Will Londo find redemption as Lady Morella says he has three opportunities to look for?