OpenSignal releases a report every now and then that shows the state of the four national US carriers' networks, and they've recently released the report for the fourth quarter of 2016. T-Mobile and Verizon are basically tied for overall best network, with Verizon ruling the roost for 4G metrics, while T-Mobile wins 3G speed and latency by a pretty big margin. T-Mobile and Verizon each took home four awards, and got a draw on 4G and overall download speeds. AT&T and Sprint each have their own strengths and weaknesses, but neither manages to net awards or even bypass T-Mobile or Verizon at any point in the charts.
T-Mobile won out in 3G download speed and 3G latency, which means that their fallback in areas where 4G is unavailable will be the fastest. AT&T was a somewhat close competitor, and everybody else's 3G networks pale in comparison. Verizon, meanwhile, won out in 4G availability and latency, with T-Mobile extremely close behind in both measures. 4G latency and availability were the only metrics where AT&T and Sprint came even close to matching the two rulers of the chats, with Sprint tying up with T-Mobile in 4G latency, and AT&T being closest behind T-Mobile in 4G availability. Regional network metrics, as measured on a per-metro basis, were all over the place, with Verizon netting top per-region scores most often, and T-Mobile predictably following. AT&T and Sprint found themselves on the regional charts in some major metro areas, but were overall unable to keep up with T-Mobile and Verizon.
It should be noted, on the regional breakdown, that there are no major metro areas where T-Mobile rules alone across the board, always finding itself hand in hand with at least one other carrier. Verizon, on the other hand, manages to handily take many a metro, such as the Tampa Bay, Florida area, New York City, and Houston, Texas. These metrics were taken over the course of the fourth quarter of 2016, which means that they don't take some Super Bowl improvements into account, and any network improvements that happened after January 1, 2017 are not on the charts. Still, this is a pretty decent measurement of where the various networks stand, and should give consumers a more educated viewpoint in regards to choosing a carrier or whether to stick with their current option.