There are numerous reasons why Die Hard is the best movie of all time.
First, it stars John Mclean as one man wrecking crew/cowboy. While he is a new york cop, he is also representative of the average Joe Shmo american. He likes John Wayne, smoking cigarettes and kicking ass and he's all out of cigarettes. Yippiee Ki Ah mother upper!
Next, Hans Gruber is the best villain of all time. He plays the best german villain since Hilter. But unlike that greasy turd he's a german with class. Mind you, at the heart of it he is just a petty criminal.
Lastly, it is set at christmas, which makes it the best Christmas movie of all time too. Most don't consider it a christmas movie but they're wrong. It takes place a kick ass christmas party at Nagitomi Tower in Los Angeles. Not to mention that there is christmas music throughout the movie.
Also it has the dude from family matters in it! I think his name was Carl Winslow. He's also a cop but he's mostly a pencil pusher now since he accidently killed a kid for jumping