What order would you recommend someone buy Switch 2 games if they have a decent Switch 1 library?
If you are just talking about games, Kirby Air Riders is the best Switch 2 game by far and seems severely overlooked in this thread, likely due to its niche. Sakurai finally designed something not Smash related, and as always, put 100% into the ordeal.
After that, it is a toss up. Bananza will be mentioned, but I personally view it as a less fun Odyssey. The break mechanics add a little too much freedom to the game and the world design just isn’t as memorable as Odyssey because of it. Besides the end, Bananza lacks that punch Odyssey had.
Pokopia is very good if you want an Animal Crossing / Minecraft hybrid. Your mileage will be based around how much you like creative / design sandboxes.
Mario Kart World is my personal recommendation for a second game. I love the newfound chaotic nature of it with its 24 racers and Wacky Races premise. The trick mechanics have never been better, making the game have a nice bounce and wide array of options. Open World provides decent content, including a large sum of challenges that feel very DS Mission Mode.
Mario Tennis Fever is fun, but it is a Mario Tennis game, so it wears its welcome. Great roster and probably the best gimmick of the series. If it wasn’t for the lack-luster Story Mode, it would be pretty much flawless for the type of game it is.
I would say: Kirby Air Riders > Mario Kart World > Pokopia > Donkey Kong Bananza > Mario Tennis Fever
Currently playing through upgraded Wonder, which is also a very strong recommends for either the game or DLC upgrade. Mission mode is fun and I love the Koopaling battles.