My Switch didn't even have a microSD, went to Amazon nearly a week ago, got me the Micro SDXC UHS-I 256 GB
https://www.amazon.com/SanDisk-256GB-microSDXC-Memory-Adapter/dp/B0758NHWS8
256 GB may be too much? but it was 31.99 at the time so i just picked it up, works fine, the Switch updated and formatted altogether by itself and it no problems so far.
I use San Disk and that is the only brand I'll use. All of the other brands always fail for me. Plus, only get your micro SD cards from big retail stores or big websites. That helps the return process go smoother if you have issues. Check this card out https://www.amazon.com/SanDisk-256GB-microSDXC-Memory-Adapter/dp/B0758NHWS8