What allows for something to be a common favorite?

It depends alot on how many people are being asked the question, lol. It's also all based on personal preference so opinions will always vary. It's sometimes in the details that the common favorite breaks down a bit. When you consider cars, they change from year to year, so the opinion will also change based on which year you're discussing. While I like some Firebirds, I have a preference for a Corvette, though I'll never have one. I like the 1973 much better than the newer models, but that's just my preference. I happen to like the sleek lines and chrome of the 73 model. ;) ps. I like peanut butter or oatmeal raisin cookies better than chocolate chip most of the time.