Verizon (VZ) may be the only alternative in some more remote areas, but after 18 years of VZ price increases and mediocre customer support, I moved my family plan to T-Mobile and new LG G4 phones (except daughter's 6 month old iPhone6). In my first five months, I can't begin to say how happy I've been with that decision.
I've driven from Seattle to Chicago - very few coverage issues (using WAZE and streaming music most of the way). Yeah, some areas only 3G, but, that was fast enough to do what I wanted to do.
I've traveled with my phone in Canada, UK, Netherlands, Germany, Czech Republic, Slovakia, Hungary and France. Had unlimited data, texting and phone coverage in all as part of my normal T-Mobile service. (would've cost me over $20/month/line extra on Verizon for equivalent - not to mention the higher plan cost to begin with). And WiFi calling is part of our T-Mobile plan ($6/month per line extra on VZ). WiFi calling is huge for my daughter who is studying abroad. She can call the US for free from any WiFi connection. (vs $1.99 per minute on a VZ phone)
The LG G4 on T-Mobile has been a wonderful device for voice, data and camera. T-Mobile 4G in the USA is faster than Verizons. And in New York city, my T-Mobile phone worked inside buildings where my Samsung GS3 on Verizon never worked. Also, at my home on a hill east of Seattle, Verizon coverage was erratic. Before spending $250 on a VZ Network Extender, any phone call over a few minutes would drop. Not so with T-Mobile. And of course, if I use WiFi calling, there's no coverage issue at all. (AT&T has never worked inside my home)
The LG G4 camera is top notch. The full manual mode permits me to get low light / night shots that would be impossible otherwise. I can get good photos at jazz clubs etc. without a flash. Great night shots of beautiful European cities? No problem. And the 16 megapixel resolution is excellent for panoramic shots.
On an overnight train from Prague to Budapest, I was able to bring up Google Maps from inside my sleeper car to follow our track, and was texting my wife back in the USA. From the middle of nowhere in Slovakia, inside a metal railroad car! So to say that I'm impressed with my LG G4 and T-Mobile service is an understatement. The LG G4 battery life was good, but heavy use of Google Maps to navigate will often mean a mid-afternoon quick charge is needed. With a Qualcom certified fast charger, 20 minute charge makes heavy use all day a sure thing.
Does Verizon suck? No. IF you are willing to pay their high price for service, and willing to put up with mediocre customer service. In my case, T-Mobile is a much better value with (so far) no apparent downside on coverage. (in fact, for international travel, I've gained a lot of functionality for a much lower cost than when we were on Verizon).