Network reliability is a tricky subject because there are several factors at play. There’s the issue of overall coverage by area, which is different from the reliability of signal and data speeds within that area.  So, to begin answering this question, we’ll say that Verizon has the best overall coverage by area. You can get a good 4G signal in more places with Verizon than with T-Mobile or AT&T. But, that doesn’t necessarily make Verizon the most reliable network in every city or town.  For instance, in OpenSignal’s 2023 4G Mobile Network Experience Report, T-Mobile actually has the best overall download speed and upload speeds. This means that the networks may be more reliable (within their given coverage areas) for things like streaming video or playing games, even if they don’t have the largest coverage area by size.