Fellowship of the Rings
has some of the most impressive visuals ever seen on film and they hold up because they rely on much more than just computer graphics. Production design is astonishing, color palette is gorgeous, costumes are stunning... Howard Shore's score is beautiful, inspiring, a true joy to listen to. Actually, the only thing wrong with the movie is Elijah Wood's SW prequel tier acting (calling it "wooden" would be a shitty pun, IMO).
Liv Tyler is utter shite too, but since Arwen doesn't get much screen time anyway, it doesn't affect the movie all that much.
The Two Towers
is generally considered the weakest part of the trilogy, but it happens to be my favorite. It suffers from bad pacing, feels dragged out at times (most of the stuff with Ents bored me to death, so I just skip it when I watch)... But the battle of Helm's Deep is a first rate thrill ride, and the music alone gives this movie high re-watch value.
Return of the King
however is a deeply flawed, soulless clusterfuck with too many endings and an abundance of cringe worthy cheesiness. Still infinitely better than The Hobbit movies, though.