I grew up with and enjoyed Gen II a whole lot, mostly because of the two areas and Psychics not being 100% the best. Even after playing later games, I still thought that Gen II was my favorite. However, now I’ve begrudgingly put it in second after playing Sun and Moon. Gen VII did away with a lot of the outdated or just plain annoying mechanics that had just kept being brought forward. I also really enjoyed what they did with some of the fights with the Totem Pokemon, especially the Grass trial. Plus the writing and translation were amazing and hilarious, especially with Team Skull.
As for my favorite pokemon, it would have to be Smeargle.
I’m not 100% sure why. I guess I just like Blue Mages, and getting access to every single move in the game is pretty amazing (except for Chatter, which is a damn shame). The only thing that makes me sad is that its stats are garbage for doing anything other than support type moves. I also like its design, and it totally looks like it would be a hipster, even though that has nothing to do with why I like it.
From my Moon run, I do also really enjoy Incineroar, and I even named mine “RKO”. I also managed to pick up and use a shiny Slowpoke, which gave me more of an appreciation for it in general.