As a current T-Mobile customer and former AT&T and Verizon customer I think I am qualified to respond to the CEO's comment. If anybody's network is crap it is T-Mobile's. They do not have anywhere near the 4G coverage their maps show. I travel a great deal and except for the big cities I get no 4G anywhere. It's all EDGE. Painfully slow EDGE. AT&T on the other hand has 4G and/or LTE everywhere I go. When I'm in rural areas or small towns T-Mobile has no coverage at all and has to roam on AT&T.
Having had T-Mobile, AT&T and Verizon, after my contract is up I'll be going back to AT&T. Overall, they have the most consistent coverage, although nobody is perfect and covers all areas. I've also used my AT&T phone in many countries without a problem. I had a lot of dropped call issues when I was on Verizon's network.
Just my 2? worth as a customer of those networks. I've never been on Sprint, so I can't comment about their network.