I'm really surprised that no one mentioned The Matrix trilogy (except from that scene from the third one). Hidden meanings, old ideeas with a new twist, based on asian legends, stories or anime. It also was a big hit when it came out, with a meaningful phylosophical question, so yes, I'd say Matrix... but then again, that's just my opinion. As for the ones already mentioned:
Harry Potter- great series, but mostly different directors, which have done their job almost flawlessly, but you can feel the difference(+ some things they missed while making the movies, that turned out to be important in later movies, due to the fact that the books were still being written). Somewhat of a letdown from the books, but the first three and the last movie were sublime.
Lord of the Rings - again, great job from Peter Jackson to take on such an epic saga and turn it into a movie, but it's disqualified for being a book almost 50 years before the movie came out. Exactly as expected, Epic.
Star Wars- trying to reboot and finnish the series (from the begginning), a great trilogy set of prequels(not to mention I personally got a shocker when I realised that it was the republic that turned into the empire, not taken over by it...note: Tried to avoid all possible spoilers until the third movie of the prequels came out). It's not anything new, so that's not it.
while I wasn't able to apreciate the original Star Wars trilogy when it came out(lack of age), I had the unique opportunity to(just for the 90's), to get a boom of out of the country movies that were a big hit (nothing before due to... strict... never mind, it's a long story). So I caught them in the late 90's, and they were still pretty new technology and ideeas here(after that, it caught up in a matter of a couple of years).
The Matrix on the other hand (except for the somewhat dissapointing fact that everything is solved with a city-shattering battle between two people in vr), the ideeas behind the plot, the simple brain teaser it was, superb for the time.
just my opinion
Edit:
GeorgW said:
They're all good choices (except LOTR, wrong generation), so just to screw with y'all I'm gonna vote for the Matrix!
mentioned before, sorry, didn't see page 2