Yeah, I’d almost say it’s an essential purchase. I buy a fair few online titles and I’ve found my 128Gb SD to be a bit lacking. I’m considering upgrading to a 256Gb or 512Gb but they’re still too expensive at high transfer rates.
If you have to choose between capacity and transfer rate for an SD card for a Switch, go for transfer. I had an old slow card and that was abhorrent for load times and stuttering on games that were stored there.