What about the T-Mobile speed tests since this is a thread about T-Mobile?
The OP said that he was considering switching. You had mentioned your poor speeds on Verizon and AT&T, so I wanted to share my experience as well.
With regards to T-Mobile speeds, I did do the T-Mobile test drive and tested it side by side with my Verizon Note 3 back in July 2014. I realize it is dated, but my understanding is that you are allowed to do only one test drive. I would gladly retest.
As I said before, I work in a high rise amongst multiple high rises. It doesn't get more urban than this. From what my co-workers on T-Mobile are telling me, speeds at my desk at work seemed to have dropped dramatically on T-Mobile since the speed tests that I did on my test drive.. At some other parts of the building, my co-workers were telling me that T-Mobile data is very flaky, and almost non existent, and missing calls. Verizon in those parts is slower, but still provides very usable speeds. In the underground parking structure at my work, 2nd level below ground, T-Mobile gets no signal. Verizon gets a very faint 1x signal (not enough to do speed tests), but I can make phone calls and Google voice texts and hangouts sporadically work.
At home(9 PM tests), T-Mobile dropped to 4g and Edge downstairs, and speeds really tanked. Verizon slowed, but maintained decent 4GLTE at the same locations where T-Mobile lost 4GLTE.
At the time of the speed tests, T-Mobile had wideband LTE deployed in my area (15+15Mhz), and Verizon had 700Mhz (10+10Mhz) and XLTE (20+20Mhz) deployed in my area.
Finally, in some spots of limited connectivity, T-mobile speed tests have gaps due to not being able to complete speed tests.