Right now I really like Tapu Lele; she looks so adorable! Plus it's really strong with its Psychic-type moves thanks to Psychic-Terrain. I think Lycanroc and Tsureena are pretty cool Pokemon too! I loved using them during the Sun run. <33
Bewear, Decidueye, Mudsdale, and Minior are my favorites. They ended up being very valuable in my team, especially Mudsdale!
If we're going to count Ultra Beasts, legendaries, and Alolan forms, I would have to go with Kartana, Solgaleo, and Alolan Ninetails. I'm not going to lie, the only reason why Solgaleo is on this list is because of the main story.
Well, I still think Primarina is badass, but since then I've grown to like more gen7 mons from using them in my playthrough, particularly Palossand and Araquanid. Araquanid especially, it's really tanky and the one I had could hit for decent damage as well. I also think it's design is really cool.
my absolute favorite is definitely mimikyu. i loved it from the moment i saw it! then that song about it came out and ... ;o; i fell even more in love. it's just so cute and misunderstood. litten is a close second, though!
hm...now, for me, its hard to say at this point. I'd maybe choose comfey or golisopod as my favorite gen7 poke. I may love decidueye the most when i get my competative one rolled....if its tactic works...
Lycanroc-Midday and Tsareena take the cake for me. It's been 16 years of Pokemon for me and Lycanro and Tsareena are on the verge of being my first ever lvl 100 Pokemon. Just to give some context to my love for those two.
Tapu Fini - It's pretty and it works well in battle as a helper to the rest of the team.
Magearna - Its concept as a mechanical Pokemon is also very interesting, and I love its appearance as this clockwork, princess-like Pokemon.
Golisopod - As soon as I heard Guzma's theme and saw him toss this Pokemon out, I fell in love instantly. It looks so menacing, and it has an amazing move in First Impression. I just love Bug types now, after them being so bad for so many generations, so long as we ignore Scizor's existence in Gen 2.
Mimikyu - I like it just because of Disguise giving it a free turn and it hating Pikachu. Next.
Pheromosa - SO FAST, SO STRONG. As soon as Gen 7 competitive started up, I spammed this thing a bunch and loved every minute of it. It's probably the most fun Pokemon I've used this generation thus far.
Nihilego - The plot importance it had, along with its cute(?) looks, earned it a spot as one of my favourites as well. Its typing is also amazing; Rock/Poison's never been a thing before, and Nihilego does it very well.
My favourite is Salazzle.
When I first saw her leaked, I've immediately fell in love with her design. She almost feels snake-like due to the expanded mouth and serpetine eyes while still looking like a lizard. The fact she can erupt the flames with her tail, hands, and feet is a pretty cool touch. Furthermore, I like her simple colour scheme.
Second is Silvally. Simply put, it's a well designed, creative mecha-griffin Pokémon with a fish fin instead of a lion's tail.
And then there's Kommo-o. When I first saw it leaked, I wasn't a huge fan but now I can appreciate how goofy and decorative the design is.
I'll have to come back once I've beaten the game (up to the third island atm) but my favourite so far/at the moment is Bewear. Part of it is because of the anime - before the anime I didn't really have any feelings for Bewear, but I fell in love with it instantly after it first appeared there. It's been really strong in battle so far and gets me quite good coverage, and the more I've used it the more I've started to like its concept and design.