I liked Iron Man vs. Iron Monger in the first Iron Man. It was the first final battle of the MCU and sort of established Tony as a superhero in-universe.
Thor vs. Hulk on Sakaar! It had suspense, humor, and great action! It's one of my favorite scenes in the movie. We finally get a glimpse a Hulk's personality. Most importantly though, it sets Thor up to be even more powerful and self actualized.
Cool to see someone else agrees Daredevil S3 had some of the best fights of the entire MCU! I would have chosen DD V.S Kingpin at the end of the season after Bullseye was out of the picture if it wasn't for that pesky Avengers qualification they thew in there.🙄