Hmmmm, preciouses, wethinks maybe...
1) Boromir's ultimately rocking speech in EE TTT
-well, no, Middle Earth doesn't rock, it simply isn't on that scale.
2) something like a tie among Boromir's last stand and his speech at the Council of Elrond and collectively the Isengard scenes (the hammers and fires and armies! Ahhhhhhhhhhhhhhh!)
3) (What an excuse to watch the films again!
) the exchange of catapult and trebuchet missiles in the ROTK
4) The battle at Mt. Doom (I know he was hardly there, but Gil-Galad ruled!)
5) a tie between the Ride of the Rohirrim at Pelenor Fields (shivers down the spine when they all roared "Death"!) and Theoden's realizing that it might be cool if he rode out with about 5 other guys when the gate broke in. Then he charged forth, horn blowing, Howard Shore's awesome music playing, and finally wearing that sweet horse helm.
P. S.
Some one above mentioned the Elves marching into Helm's Deep.
One time I saw it, it was great. Wonderful music.
Another time I watched it, I thought of nuns processing into a Chapel (excuse the bows), I mean, many of the elves in the movies resembled women, and those particular elves wore the cloaks and was kind of dark (understand?).