Honestly everyone should just use T-Mobile Connect. They make it very hard to find on their site, but it's their true prepaid service, cheapest plan is 5GB of data and unlimited calls/texts, and it won't a lesser priority like MVNOs are.
The fact that people pay over $100/month for a phone bill is truly a uniquely mind-boggling American thing.
Depending on the MVNO you can get first-class priority data (my plan has it), but also this stuff has never made a difference in my experience. When I was on 'lower priority' data the differences in speed weren't noticeable if I had service at all, and in the cases where I was at some event where there was a lot of devices contending for access to the tower, nobody was getting service.
The fact that people pay over $100/month for a phone bill is truly a uniquely mind-boggling American thing.