It would be probably too easy to mention Finale/End Title pieces that cap off with a great blast/fanfare/timpani roll. There are many excellent examples. John Williams alone did literally dozens of those and I can't name a single favourite (probably E.T., if I'm forced to choose). Jerry Goldsmith also did many.
However, I'll try to make a different list of great ending pieces, not necessarily the absolute top, but five that stick out in my mind right now:
. 1941 (Williams) -- Just when the orchestra reaches the climax, Williams still has something left to say: snares continue to roll and then the march rhythm continues, but this time it's just two piccolos that take the final word. Absolutely love the final "boom-tzzz", a sort of wink-wink to the people who stayed until the last frame of end title roll

. THE BLUE MAX (Goldsmith) -- A dirge for the fallen hero, but Goldsmith doesn't forget to look again at the joy of flight. Absolutely fitting.
. VERTIGO (Herrmann) -- A classic. The whole 7-minute final sequence is a masterpiece, but I'll concentrate on the last couple of minutes: the Wagnerian love theme returns with empathy when these two characters seem to have found their happiness and Scottie is able to defeat his own deepest fear... but then an eerie electric organ chord underscores a nun coming out of the dark... Madeleine faces her own destiny and then Herrmann unleashes his entire orchestra to a true operatic finish to say: "This man is now completely lost". This is not "just" film music. This is a piece of art.
. THE MISSION (Morricone) -- A solo boy soprano intones a sad "Miserere" to comment on the whole tragedy. But pan pipes have a last, ominous say. Chilling.
. EMPIRE OF THE SUN (Williams) -- I always thought it would need a real gut to walk off such a powerful, intense story with a children chorus singing exsultate justi, hallelujah... but it's so perfect and fitting that none other piece of "dramatic" music would have had the same impact. Williams pulls out all his stops and delivers a joyous, exihilarating, complex choral piece that isn't like anyhting he's ever done before. This is the music I want played at my funeral
