I have been using T-Mobile for years. Coverage is iffy, highway especially. I’ve been testing Consumer Cellular for abt 4 months. It’s iffy too. I surf more than talk so coverage and speed is imperative.
T-Mobile was better b4 teaming with lousy Sprint. ConCell is nothing to call home about. They use lousy TM and ATT towers. When I have good signal they are great. I require better. 
My sister has Verizon postpaid on an iPhone 4. She had constant service on the highway. Mine are prepaid services running on Motorola G Power 2021. I’m going to try Verizon prepaid next. Ahh, the joys of an unlocked phone. 