I was shopping for a good ARPG to play on my Switch. So which one would be the better pick-up? D2R or D3?

Well, D3 is a very fast-paced and super flashy in-your-face arcade feeling game. While D2R is much slower-paced. Diablo 2 requires far more time and dedication to get far into higher difficulties, and don't mention there will be a new Ladder system that will make its way into the game in early 2022, a host of brand new D2 items and features will be introduced. So you might need to buy D2R ladder Items just in case. While D3 you will be going to higher difficulties within an hour or two.

Diablo 2 Resurrected is for you if you want a dark, gritty experience and want to feel like you’re on a quest to kill the lords of hell. Diablo 3 is for you if you want to turn off your brain, murder demons, and get loot. Honestly, for me, it just depends on my mood most of the time.

Overall, Diablo 2 Resurrected is a better game; story, character creation, build, itemization, atmosphere, music are all better in 2.