As a standalone entry, Avengers Endgame is not in the top 3, heck not even top 5 of the MCU movies. Better character development, action sequence and - dare I say it - CGI are found elsewhere (focus on Thanos the whole movie and you will see).
However, as a culmination of decade of magical movie-making, and an ultimate payoff to our emotional investment in these characters, Endgame does it perfectly. Left the theatres feeling similar to how I felt after Dark Knight Rises and Logan.
4/5 stars as a standalone movie
6/5 stars as the finale of Avengers