Star Wars had six films that form a complete story. The first half is how Anakin SKywalker goes evil and the protagonists lose, the second part is how Luke Skywalker saves and helps the new Rebels undo it. As far as I am concerned, those six movies are the definitive story. Rogue One and Solo will likely be safe supplementary material in the long run.
Rogue One is better than 1 2 and 3 in terms of most acting and general storyline and realism (bothan suicide mission) and fits very well into the 4,5,6 storyline. Its basically 3.95.