Damn I wish I'd seen your thread earlier...
Damn tests/exams [sigh]
Anyway what was wrong with...
Koch (the second Koch

)
The human (can't remember his name) who was an agent of the shadows.
G'kar's body guard (can't remember his character name, but played by buddy stevenson I believe).
The blonde haired ex-psi core telepath, Byron? (if you like good guys)
I would've gone for chekov (can't remember his character name either) in his psi corp regalia; with the slogan 'we are the psi corps, you must trust us'!
Or perhaps something more obscure...
Delen's Vorlon inquisitor - Jack (awesome episode).
Or Gary Cole (Excalibur captain) - from the Last Crusade
Peter Woodward (son of Edward) - the technomage, bit of an over actor (like father like son I guess), but still a good character.
Alas you have already chosen, I like G'kar from the early season, his games and interplay with Londo - made for good entertainment. They made him too much of a wimpy good guy in the end.