Martin Crane is the king of sarcastic comebacks, so here's a collection of his best lines and retorts according to this post in the r/Frasier subreddit:
  / round_three_weve_done_niles_and_frasiernow...  
The clips are shown in the order they were posted. Wow, some of these were really tough to track down. I've done my best to locate each clip but my apologies if I've missed any.
The series and episode from which each clip is taken is shown in the overlay at the lower left of screen.