If you're a "Star Wars" fan, you probably have at least some opinion on what order is the best to watch all of the movies in. Some prefer to watch in chronological order, starting with the prequels and moving forward, while some think watching in order of production makes more sense. Neither of these orders are ideal, since one requires starting with the prequels and introducing "Star Wars" with what most agree are the worst movies of the series, and the other requires coming up on "The Force Awakens" on the depressing note "Revenge of the Sith" leaves behind. So, in an effort to figure out how to make the prequels fit into the series in a tasteful way, "Star Wars" fans created the Machete Order, or watching the movies in the best order to emphasize Luke's storyline: 4, 5, (1), 2, 3, 6, 7, presumably followed by 8 and 9, once they are released (Episode 1 is optional, as it is both bad and doesn't include details necessary to understanding Luke's story, unlike Episode 2, which, unfortunately, is necessary). This order lets "The Empire Strikes Back" end on a cliffhanger and uses the prequels as a flashback that emphasizes the parallels between Anakin's fall to the dark side and the path Luke is on in the present, making Luke's first appearance in "Revenge of the Sith," face hidden by black robes as he uses the force to choke Jabba's guards, far more poignant. The order allows the prequels to add to the story rather than bog it down and has become a fan-favorite, especially as a way of introducing someone to "Star Wars" who has never seen the films before.
Before "Rogue One" came out, most fans assumed it wouldn't be included in the Machete Order, since it's a stand-alone film and wouldn't be necessary to Luke's storyline in the same way Episode 1 isn't. When the movie was released last week, though, those fans began to realize that the movie was worth including when rewatching the series, unlike Episode 1, meaning "Rogue One" has to be worked into the watch order somehow. Since the movie doesn't have an effect on Luke's character arc, the film either has to be placed at the end of the standard episodes or the idea of organizing the films based on their relation to Luke must be abandoned so that the film can be placed into the watch order in the way that makes the most narrative sense.
The most obvious way to incorporate it would be to place it before Episode 4, since the events of "Rogue One" lead straight up to the very beginning of "A New Hope" and fills in gaps and holes in the film. "Rogue One" serves as an exciting and enjoyable start to the series, which is essential when beginning any watch order, especially for the first time. However, though this may work for those who have already seen "Star Wars," it may not be the best introduction to the entire franchise for a newcomer. Yes, it does work as a film on its own and function well as an introduction to the two sides of the war, the Empire and the Rebel Alliance, but it's a rather clumsy introduction to aspects of "Star Wars" that will become important later on, like the Force and the Jedi. It also feels so completely different from the rest of the "Star Wars" films that I assume it would be a little strange to be introduced to the series through "Rogue One" only to have the rest of the films be so separate. "Rogue One" may be the best place to start as someone who has already seen the films and can function as an introduction to the series in some cases, it may not be the best choice.
The best alternative to this may be to watch "Rogue One" after Episode 3 and before Episode 6. This way, the film allows the audience to see the creation of Darth Vader and then get to see him in his prime after "Revenge of the Sith," and also acts as a crossover and reintroduction to the original trilogy from the prequels, since it takes place between them. It does distract from the main storyline a bit and may take away from the impact of seeing Luke in the same dark robes in "Return of the Jedi" as his father in the end of "Revenge of the Sith" since there is an entire film placed between them, but if "Rogue One" isn't placed at the beginning or end of the series, this is the best solution I can think of. Once "Rogue One" comes out on DVD and can be tossed around the order once its made available, the best way to watch the films will hopefully become clearer. Until then, and most likely even after, the best way to join "Rogue One" with the Machete Order may remain up for debate.