Least Favorite: Kakashi VS swordman of the Mist. He is my fav and was supposedly pissed when he fought them. He was suppose to let loose with his rumored 100 copied Jutsu....and didn't. I was so disappointed
Favorite: Sasuke vs Itachi, Sasuke vs Deidara, Naruto vs Neji, Lee vs Gaara, Naruto vs Orochimaru. Vote Naruto vs Sasuke. Naruto and Sasuke vs Momoshiki.
Konan vs 'Madara' was my favorite fight, or at least it is high on my 'list'. I liked how well Konan was prepared and the final jutsu that she activated. Not to mention the chilling atmosphere either.
My favorites would be Shikamaru vs Temari, Shikamaru vs Tayuya, Sasuke vs Itachi, Sasuke vs Deidara, Neji vs Kidomaru, Konan vs Obito, and Lee vs Gaara.
However, my least favorites would probably be Naruto vs Sasuke VOTE 2, Leaf Ninja vs Kakuzu (and Hidan, but mainly the fight with Kakuzu and Team Asuma), and Kakuzu and Hidan vs Yuugito Nii.
The reason for disliking VOTE 2 so much is probably because at that point I lost interest in the series and the fight that was built up for hundreds of chapters. I dislike the fights with Kakuzu and Hidan because I found them to be a bit boring and I don't really like the duo all that much.Regarding my favorites, it's mainly because of the use of tactics in them, even if in some there's only a bit. In regards of Konan vs Obito, Lee vs Gaara, as well as Sasuke vs Itachi they were just a bit memorable. Gotta love Kirin.
In the manga...that's a bit hard, but ultimately I'd have to go with Naruto vs Pain as my favorite and Naruto and Sasuke vs JJ Madara as my least favorite.
Favorite:too many to choose from but some good ones were pain v naruto, sasuke v itachi, sasuke v deidera, third v oro w/ nardo v gaara, and both sasuke nardo fights