One nice nerdy way to view SW canon is to follow the creator’s/creators’ intentions. For example, since Lucas himself has ruled the unaltered OT ‘non-canon’, it’s fair to say that these stories (and their accompanying optional EU) constitute one canon. The prequel outline as discussed by Lucas and Kasdan circa '81 marks the accompanying backstory to that particular canon, including the notion that Leia’s mother died when the twins were toddlers.

The SEs are designed to fit with the PT, so that’s another canon right there (again with optional corresponding EU). Here we get Midichlorians, the Chosen One prophecy, a younger Anakin, Kiwi Boba, and so forth.

With the ST it gets tricky, given that despite Disney’s canon declarations it is clear that JJ Abrams favours the unaltered OT (Han shot first according to JJ) while Rian Johnson seems keen to mention Darth Sidious out loud. At this point canon becomes somewhat a la carte. Clearly the old EU no longer applies though.

For me, during my crankier moments, my canon consists of Star Wars and Empire (unaltered) with Revenge of the Jedi still yet to be made…