As a few said, lets just agree the first film is the BEST(cause it's killing the poll) and banter about the rankings for the others.
I voted for 1 & 3 cause we could. Since those are linked via the brotherly connection Vengeance works great as a sequel to the first film. SLJ is a great "in tow" sidekick that Officer Al only wishes he could've been. So those kinda tie for first imo.
My very tight second place goes to Live Free or Die Hard. I wholly agree with the others that it's overly bashed on the internet(like IJ:KOTCS). People I know offline who aren't on any msg brds never say crap about it. Great cast, fun to watch and this film really illustrates how even though this has come to him again he's going to do what needs to be done. He tells Matt Farrell he "hasn't done this kinda thing in a while" that "if there were anyone else available to do it, he'd let them, but there isn't, so we're doing it". It's McClane accepting what needs to be done, just like the first film. Reluctant honor bound cop.
I don't dislike DH2 but something has to be last. The night custodian Marvin makes for a great comedic "in tow" character here. William Sadler makes for a great bad guy to really hate. With John Amos as the turn coat for hire helping him from within. When I finally saw this on VHS for the first time circa '92 all I knew him from was Mr.McDowell from Coming to America so it was fun to see him play "McClane's kinda asshole".
So my ranking:
Die Hard
Die Hard with a Vengeance
Live Free or Die Hard
Die Hard2: Die Harder
I'm attending the Regal Theater all day Die Hard Marathon tomorrow starting at 12 noon culminating in the 10pm-ish debut of A Good Day to Die Hard. Ending I guess in time to start showing the "official" midnight shows.
If they make a Die Hard 6, it needs to be called "Old Habits Die Hard", and I'm guaranteed in the theater!
That's a great title, you should purchase the URL now just in case.