Yup those by Delenn and Zathras have GOT to be the best.
I might add:
"Our thoughts form the universe, they always matter."
G'Kar, The Hour of the Wolf
We are not now that strength which in old days
Moved earth and heaven; that which we are, we are;
One equal temper of heroic hearts,
Made weak by time and fate, but strong in will
To strive, to seek, to find, and not to yield.
Sheridan, The Long Night
"No regrets then?"
"A few. But just a few. You?"
"Oh, enough to fill a lifetime. So much has been lost, so much forgotten. So much pain, so much blood. And for what, I wonder. The past tempts us, the present confuses us, and the future frightens us. And our lives slip away, moment by moment, lost in that vast terrible inbetween. But there is still time to cease that one last fragile moment. To choose something better, to make a difference, as you say. And I intend to do just that."
Centauri Emperor and Sheridan, The Coming of Shadows
and of coarse
"What do you want?"
"I'd like to live just long enough to be there when they cut off your head and stick it on a pike as a warning to the next ten generations that some favors come with too high a price. I'd look up at your lifeless eyes and wave like this. Can you and your associates arrange it for me, Mr. Morden?"
Morden and Vir, In the Shadow of Z'ha'dum
and
"There, you see! I'm going to live."
"So it would seem. Well, it's an imperfect universe."
"Bastard."
"Monster."
"Fanatic."
"Murderer."
"You are insane!"
"And that is why we'll win."
"Go be the ambassador to Babylon 5 they say. Will be an *easy* assignment. Ah, I hate my life."
"So do I."
"Shut up!"
Londo and G'Kar, Convictions
and last but not least "JUMP!!! JUMP NOW!!!" Always chilling and exciting at the same time.