Even though I played Sun first I think Lunalacrozma is more nicer, so I might just go with UM this time until further exclusives are announced. I honestly hope there are new Pokemon/formes or let alone new features, Sun/Moon were stale tbh, but that's the first paired games of a gen for ya.
Also, doesn't Ash have a Rockruff in the anime that people speculated to evolve into said forme?