Here are a few:
Early Watcher Wes:
"Remember the three key words for any Slayer: preparation... preparation... preparation."
"I didn't get this job because of my good looks."
"All right, everyone. Monsters, demons, world in peril?"
"Everybody does seem to be going a bit mad lately. Faith has something of a head-start."
"I'm a Rogue Demon Hunter."
"Butcher an innocent girl, will you? I'm going to thrash you within an inch of your life. And then I'm gonna take that inch."
"As a point of courtesy, I like to get to know my opponents before I engage them in mortal combat. Do, uh, do you have any hobbies?"
"We might try shouting fire...It's not technically a crowded theater."
"These pants tend to chafe one's...legs."
"You know, back in my days as a rogue demon hunter, I once used that very spear to pin down what I thought was a small Rodentius demon. Of course, the poodle's owners weren't very happy."
Dark, badass Wes:
"There's love. There's hope...for some. There's hope that you'll find something worthy...that your life will lead you to some joy...that after everything...you can still be surprised."
"There are things worse than walls. Terrible... and beautiful. If we look at them for too long they will burn right through us. Truths we couldn't bear. Not every day."
"I stabbed you. I should apologize for that. But I'm honestly not sure how. I think it'll just be awkward."
"I don't know what kind of man I am anymore..."
"If you've come to tell me you killed your parents, could it wait until another time?"
"There's obviously not going to be any big swirly hole jumping without a big swirly hole."
"As far as evil plans go, it doesn't suck"
"I've seen a darkness in myself. I'm not sure you'd even begin to understand"