Some good examples here. I’d just mention a few other memorable dialogue scenes:
all the scenes of McCoy with Spock’s Katra in ST:III, including lines like “Yes, Genesis! How can you be deaf with ears like that?” and “Where’s the logic in offering me a ride home, you idiot? If I wanted a ride home, would I be trying to charter a space flight?”
in Star Trek IV, the scene with Kirk and Spock in Gillian’s pickup, with Nimoy doing his best Gracie Allen impression. Also, the “No dipshit” bit in the restaurant.
Some good examples here. I’d just mention a few other memorable dialogue scenes:
“I love Italian. And so do you.” “Yes.” My favourite bit in TVH.