IE, what secondary attribute do you use to attribute greatness to a game? Price, writing quality, playtime, etc. Maybe a limited question, but we'll see.
Personally I'm all about hour counts. Whenever I get a good game the first thing I usually cite is how many hours I've put into it so far. My favorite PC games have been RPGs like New Vegas / Skyrim / Borderlands / Mass Effect where you can easily rack up hundreds of hours.