It was difficult to give a definite answer as to which of the X-Men series and the Avengers series was better because everyone's aesthetic and preferences were different. Both series were very successful and had many fans. If you like sci-fi and superhero movies, you might prefer the X-Men series. If you liked teamwork and battle scenes, you might like the Avengers series more.
When watching these movies, you can also choose to watch only one series or both series to better understand the structure and storyline of the Marvel Universe. In any case, these movies were worth watching. They could choose according to their own interests.
The X-Men are part of the Marvel Comics lineup. They have their own unique place within the Marvel multiverse, with a dedicated fan base and a significant impact on the comic book world.