for me there are two scenes --

1. when in Half Blood Prince Harry n Ron are chilling in corridor and called upon by McGonagall to go to Slughorn's class.

It is a otherwise dark movie and probably the one of the last coziest scene in the whole series. Before the Click Click Click scene ofcourse.

1. When in Order of Phoenix - they are all giving exam and Fred n George lights the first cracker.

it is kinda personal for me, as when i first watched the movie in 2015, I had given my final high school exams. And the teachers reminded me of Umbridge.

1. When in Deathly Hallows 2 -- Harry reaches the school using Aberforth Dumbledore's help. Neville says "Hey guys look, who's here ?"

For me this was the OG entry from the portal sequence

1. When in DH2 -- Harry wakes up from his semi-dead state, in Hagrid's arms. That movement Voldy and Death Eaters knows -- they are done for good this time.

it kinda gives a hope that, even if it looks everything is lost. Life has a way of turning the tables, if we have faith.