i switched to tmo last month after over a decade with verizon. i had unlimited data on verizon since 2010 and was getting discounted phones till this year. when i switched i noticed two things. verizon phones lack lte band 12 which is low frequency new gsm lte band used for long distance and deep building penetration so my reception was poor in commercial buildings like hospital. i had to sell verizon phone and buy gsm phone that included said band. with new gsm phone the reception is on par with verizon with speeds very similar, but verizon is a bit faster in metro detroit. i'm talking where verizon used to be 30-40mpbs, tmo is about 20-30mbps downspeed.
so in conclusion, verizon network is superior but i'm paying 1/2 of what i would be paying on verizon by end of next year(about 220-240 for 4 lines including taxes and fees) i'm now paying 114 for 4 lines of unlimited everything in mexico/usa/canada with very similar service. there are a lot of perks on tmo like free stuff on tuesdays(pizza, movies, dunkin donuts gift cards) and free inflight internet if you're a frequent traveler. their customer service is very responsive. i've contacted them through twitter and they always get back to me within an hour to sort out or address any questions i've had.
last time my wife had tmobile was in 2007 and it was horrible, 10 years later and it's 2nd best in the nation in my opinion.