Mobile phone/data performance is very location dependent. For the majority of people, one is significantly better than the others where they live for largely historical reasons. If I lived 50 miles east of where I do, I might prefer VZW. If I lived in DC, I might prefer T-Mobile. There is even someone here on SatelliteGuys (can't recall who), who thinks that Sprint is the best, and it probably is where they live. Overall, the top two are going to provide the best coverage nationwide, and T-Mobile is coming on strong in coverage. Verizon has great coverage where I live, but it often unusable due to how oversold the network is around here. I tried switching to VZW in December and had to switch back to AT&T, just to get decent performance. As mentioned previously, 50 miles east of me, Verizon is the bomb. On average, if you can get coverage, Verizon is going to be a little better than the others, but not always or everywhere. This is why people I know who travel a lot often prefer Verizon, even if it sucks where they live.
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