>>39934285Orre and Sevii most likely. The first is remote, desolate, and in-universe rather obscure (despite being part of the main series, it's never been referenced to my knowledge in any other game); the latter is small, dependent on Kanto, and is sometimes even considered to be a part of Kanto just like the Battle Zone is a part of Sinnoh.
As far as the "main" regions go, definitely Alola. It's just a remote, small island chain that up until recently didn't even have a proper league.
