If we’re counting dark comedy (which I do), it’s probably Parasite or Another Round. Of the more conventional types, it’s likely Monty Python and the Holy Grail or His Girl Friday.
Guess I will have to mention this underrated gem ... Life of Brian. Joking aside, some movies I want to mention are tucker and dale vs evil, death at a funeral 2007, and what we did on our holiday.
Clue (Lynn, 1985) does everything for me. The cast and script are perfect. It never shows up in "greatest comedies of all time" lists for whatever reason, but it deserves that spot just for Tim Curry's performance alone.