Verizon
Verizon’s 5G service, which it dubs 5G Ultra Wideband, is based on mmWave technology and offers fast speeds, low latency and good capacity. It’s also fairly widespread across a range of markets, and features good coverage (despite the limitations of mmWave).
Verizon 5G Ultra Wideband is available in a total of 31 cities, ranging from Atlanta and Boston to Omaha, Nebraska and Salt Lake City, Utah. You can find a full list of covered cities at this link. (But note that the mmWave 5G may not cover the entire city.)