Babylon 5 is the pinnacle of live-action sci-fi storytelling and Londo Mollari is my all-time favourite television character.
I think Season 2 is a vast improvement on the first, as much as I love Sinclair. Season 1 is great set-up but fairly standard and episodic in nature. Season 2 is when Babylon 5 really shows what it can do. It couldn't have done that without S1's set-up though which was incredibly subtle and patient.