I highly recommend Rogue One as well. It follows Cassian Andor as a spy for the rebellion immediately after the second (and final) season of the show.

Rogue One is a story set immediately before the first movie: Star Wars Episode IV: A New Hope. Immediately as in the final scene of Rogue One is the first scene of A New Hope.

Similar to the other commenter, the problem is that Rogue One is by far the best movie of the entire franchise, so you start at the high point.

If you like the movie and want more Star Wars, I recommend this order. I’ll list the title and the “episode” number

1. Rogue One (3.9)
2. A New Hope (4)
3. The Empire Strikes Back (5)
4. The Phantom Menace (1)
5. Attack of the Clones (2)
6. Revenge of the Sith (3)
7. Return of the Jedi (6)

There are three more movies after #6, but there’s almost no point in watching them.

It’s really important to remember that a lot of the Star Wars movies aren’t good but they’re cultural institutions and you kinda have to accept them as they are. The writer/director of the original trilogy spent a lot of time tweaking and editing them after their original releases including adding new scenes digitally created decades after the release.