Tello is a mobile virtual network operator (MVNO) that uses the T-Mobile network.
I have an account with them for my daughter.
The service is very good, the prices are very good with customizable plans, the dashboard (website) works well.
Very happy with them.
Twigby is another MVNO with good plans, good prices, good service.
Twigby runs on Verizon network.
I'm not using them right now, but I was always very happy with them too.