Helium Mobile's 30GB plan for 1 line costs $20 per month.
It rides on the T-Mobile network for coverage.
It includes unlimited minutes, unlimited texts, and 30GB of high-speed data per month. After your high-speed allotment, you get unlimited slow data at 1Mbps. You get 5GB of hotspot data. Video streams at 480p quality.
The Helium Mobile Unlimited plan has deprioritized data. Having deprioritized data means you may temporarily experience slower speeds during times when the cellular network is busy. You'll resume getting the fastest speeds available when the network is no longer busy.
Taxes and fees are extra on this plan. I estimate they will add another $1.38 to the price. Your total montly bill will be about $21.38 per month.
Overall, I recommend the Helium Mobile Unlimited plan because it is a good value.
You can also check out these plans with the same coverage and data amount (scroll left and right to browse plans):