…makes you laugh the hardest?
I don’t know how to answer that question, because I think it’s a time-dependent variable. I know what movies made me laugh hard in the past, though I couldn’t quantify it, but I’m not sure I’d find them as funny today, either because they would have lost something in rewatching, or because I’ve grown, or at least changed, over time, and have a different sense of humor. Obviously, something you might have found hilarious as a child might leave you cold today. On the other hand, you might have seen something as a child that your parents laughed at uproariously, but that you didn’t get. I think that a lot of young people miss a lot of humor in The Simpsons because they aren’t familiar with the cultural referents.
But just off the top of my head, I recall Blazing Saddles, It’s a Mad, Mad, Mad, Mad World, Dr. Strangelove, The Wrong Box and other Peter Sellers movies as side splitters at the time. Also Woody Allen and Steve Martin.