Having had a day to reflect on it, and discuss it with my friends and all, I have come to the conclusion that Harry Potter: OOTP is probably my favorite of the Harry Potter movies. It was all so, to borrow a word, streamlined, and while many scenes from the book were cut that would have had so much potential on film, it was still utterly fantastic. Harry Potter: POA was also really good because it was dark and all, but it - the movie and the book - was just one giant trailer for the next books/movies. It sets up some things that make major plot points possible, but it doesn't have all that much to do with the war on Voldemort.
I have to say, Harry Potter: OOTP would actually be a perfect movie to see with a bunch of school friends, or entirely insane friends, because this would be so awesome to shout stuff at.
Okay, I'm done ranting about the movie (in a good way!) for the second time in less than 24 hours.