I think SwSh is one of the best Pokemon games, but a big part of this are the DLCs, so keep in mind that I'm rating the game with the DLCs included.
- Fantastic new Pokemon: for me personally, Gen 8 introduced the best new Pokemon since Gen 4. Generations 5, 6 and 7 were kinda disappointing for me, so Gen 8 was a very pleasant surprise. Drednaw, Polteageist, Centiskorch, Dragapult and Wooloo are some of my favorites. Also Gmax forms were really awesome too, like Gmax Charizard, etc
- Some of the best Human Characters: The Galar cast is really memorable imo. Sonia, Nessa, Peony, Hop, Bede, etc, are some of my favorites.
- A beautiful region: Galar is really memorable for me as a whole, the region is big and each area feels unique, rather than a copy paste. Gleamwood Tangle, Ballonlea and Isle of Armor are my favorites.
- Amazing music: I mean in fairness, I love the music in almost every Pokemon game. But Galar's is one of the best.
- League Cards: they were very fun to customize
- best Clothing Customization in the series (I still can't believe SV restricted us to a bunch of school uniforms only, it made me value the Trainer Customization in Smash a lot more).
- 3 fantastic Wild Areas, which are quite big, but not annoyingly too big.
- Isle of Armor: this island has become one of my favorite places in Pokemon. I love the vibe it gives, the size of it, the design, the atmosphere, the plot around it, etc.
- Crown Tundra: another great area, with a lot of cool stuff to discover.