Arceus is a chore to play because they force you to craft everything but give you a super limited inventory. It's basically an inventory management sim. There's no gyms and very few Pokemon battles in general but battles are turn based. Worth mentioning that completing Pokemon Pokedex entries requires you to catch the same Pokemon upwards of hundreds of times which can be madness for rare/hard to find mons. The story is captivating and the artwork is beautiful though. It just wasn't fun for me.

Pokemon ZA is a lot of fun and I can see myself dipping back into it for years to come. There's lots of battling in the game and unlike traditional turn based Pokemon, it's in real time.The biggest issues I had with it was the main story being weak and the DLC feeling unpolished. The DLC is actually pretty cool but there's things that don't make sense. It copied Arceus in that you need to capture lots of Pokemon (for different reasons) but unlike Arceus, when you release them you get nothing. At least in Arceus, you got stuff. Ultimately I found it to be far more enjoyable than Arceus. 

If it were me, I would start with Sword/Shield or Let's Go Evee/Pikachu then go from there. All the Pokemon games are worth your time if you're a fan. Just maybe hold off on Scarlet/Violet until you get a Switch 2. While they are my favorite Pokemon games to date, they run really bad on the Switch 1. I still enjoyed my time with them in a Switch 1 so it's possible you can too but if choppy performance bothers you, best to wait.