I have a difficult time saying one particular flick is funnier than another...it depends on the mood one is in. For instance, I find Woody Allen’s “Zelig” very funny, but many people would not. They’d just consider it weird.
I also like “This is Spinal Tap”, “A Mighty Wind”, “Best in Show”, and “For Your Consideration”, but some people to whom I have recommended these pictures have watched them with a straight face and never cracked a smile.
So here are a few that I have enjoyed and believe many others would, too...they’re not necessarily “niche comedy” movies.
Funny Well Known Films:
“Murder By Death”
“Monty Python & The Holy Grail”
Any Naked Gun or Airplane! film
Now...very funny films you may NOT have seen, but are good:
“Amazon Women on the Moon”
Shouldn't you include "Waiting for Guffman" in this list?