Interesting. I've tried all three before and definitely preferred Verizon's combo of coverage and speed. I think at the time, AT&T had better coverage and worse speed, while TMo had better speed and worse coverage, so Verizon was the happy medium for me.
Recently I've been on FirstNet (because I work in healthcare critical infrastructure). It's run by AT&T and has dedicated bands/hardware, as well as data priority on the main network. No throttling or caps, tethering included. Best part is it's about $50 per month after tax, which is unbeatable for an unlimited non-MVNO carrier. Sometimes I feel like I'm cheating, but it certainly is useful for work. I try not to abuse the privilege of having it.
Recently I've been on FirstNet (because I work in healthcare critical infrastructure). It's run by AT&T and has dedicated bands/hardware, as well as data priority on the main network. No throttling or caps, tethering included. Best part is it's about $50 per month after tax, which is unbeatable for an unlimited non-MVNO carrier. Sometimes I feel like I'm cheating, but it certainly is useful for work. I try not to abuse the privilege of having it.