Honestly, reading through a lot of this thread makes me realize just how much Kalos, Alola, and Galar suffer due to linearity. I think that’s probably a huge reason that I feel like the franchise drops in quality for XY, USUM, and SwSh (SM I can forgive because the story is good enough that it made me want to progress).
Having grown up on Johto, one of my favorite things in the whole series is how you can go three different directions (two literally, but three figuratively) once you clear Ecruteak. You can take off toward Lake of Rage and deal with Price and the Team Rocket infestation in Mahogany; you can go toward Olivine and Cianwood and prioritize beating Chuck before healing Amphy; or you can mix it up and do the latter without beating Chuck, instead challenging Jasmine immediately.
That simple array of a few options has always felt very freeing. The fact that you can do something similar in Hoenn and Sinnoh, along with all the loops that allow you to easily backtrack on old areas with the benefit of new field moves to find hidden things, made the earlier regions feel so much more open. (Forgive me, though, for I honestly don’t recall if there are places in Unova where you can easily diverge from the “standard” path)
To follow that with regions where you’re largely pushed forward in one direct path, and without many (…any?) secrets and side dungeons to discover, is so very frustrating.