I've said it before, only in the context of my specific house. AT&T and T-Mobile, no service period near me. Verizon has spotty coverage in the house. Phone could be sitting on the table doing nothing and it goes from -115 dBm to No Service to -105 dBm back to No Service. Sprint gives me marginal signal from a tower 4 miles north of me on LTE band 25 in my bathroom, I could still pull in 12 - 15 Mbps though. The next closest Sprint tower is about 6 miles south of me. If 800 MHz could be deployed here, I would probably have awesome overlapping Sprint coverage. Sprints overall service improved in my general neck of the woods in between the stints I had with them.
My experience with T-Mobile and their data speeds blow me away. On rural towers I can get 100 Mbps easy. I've exceeded 50 GB this billing cycle and am subject to throttling, but so far no slowdowns. Hit 110 x 15 on Tuesday morning near work and that's about normal for me anywhere around here. While I am not a huge fan of T-Mobile, I like the investment they are making in their network. No other carrier can provide me with anywhere near 300 Mb Down/60 Mb Up on LTE.
I posted this in another thread but from my experience with all four carriers over the past handful of years, here's how I rate them in my half of Upstate NY. Verizon being oversold is right. Just about everyone around here has Verizon, expect for me and I've watched their speeds drop over the years. At work on company phones on a good day I can hit 10-15 Mbps, which is certainly better then AT&Ts no service at all, but nowhere as good as the 60 - 80 Mbps that can be had on the smaller carriers of Sprint and T-Mobile. And when I had Verizon, I was able to hit 30 - 40 Mbps on LTE, and that was back in 2014 on my old Droid DNA.
Coverage – Verizon, T-Mobile, AT&T, Sprint
Data Speeds – T-Mobile, Sprint, Verizon, AT&T