If you're into EUs, kirk55555, you should check out the Babylon 5 books. The early ones weren't authorized by JMS, but then he started taking more notice and the last 11 (two standalones, three trilogies) were canon.
Of the standalones, there's:
- The Shadow Within, dealing with Anna/Morden's Z'ha'dum backstory (if I recall correctly, the non-Z'ha'dum stuff in the book isn't canon to JMS, but the backstory is)
- To Dream in the City of Sorrows by JMS' now-ex wife, showing Sinclair's story on Minbar training the Rangers during Season 2/first half of Season 3.
The trilogies are:
- The Passing of the Technomages, which shows the Shadow War from the perspective of the Technomages (including a particular one who appears in the TV spin-off, Crusade).
- The Psi-Corps, with each book covering a different time period: the creation of the Corps, the young life of Bester and Bester as an old man and war criminal.
- Legions of Fire by Babylon 5 show writer and Trek spin-off author Peter David, which shows Centauri Prime from its last ep of S5 to Londo's death, as we see Vir's rise to freedom fighter and leader.
I'd definitely recommend the Sinclair book. The Centauri ones are my favorite, but we all know how you feel about that plot thread.
But who knows, maybe the fact that it's an A-to-B linear account of that story that really fleshes out the details and how those years were spent and that we see Vir's journey to someone who could reasonably become Emperor could make you feel warmer about the story.