AT&T announced weeks ago they are in the process of upgrading all of their towers around town, the process would take 3-4 months and service would be bad in areas where the towers are actively being worked on. I haven't noticed any problem at my house but did have a problem by Morellis last week, that's the only out of the ordinary experience I've had recently.
I've had issues with Sprint in the past, they screwed me with their billing and that left me with a permanent dim view of them. I did a job for them and saw them as a very sleazy business, with terrible management that really screwed a lot of employees and really half-assed the project. The worst cell phone experience I've ever had was with Nextel, and while I was doing the job for Sprint they merged, further sealing my dim view of them and swearing them off forever. I was never overly impressed with their coverage and frequently worked in cities (even state capitols) that had spotty coverage if anything.
Verizon was ok when I had them, but pricey. Their network still doesn't handle phone and internet at the same time and that's a big shortfall for me. Pushing smartphones but no capability for voice and data simultaneously?? Come on. I use both too frequently to be interested in giving that up, and the reviews are in they didn't handle the flood of data traffic from picking up the iphone as well as promised or hoped for.
T-Mobile was good, but I had issues with them while traveling. They don't own many towers compared to the others, and lease usage from other companies. Many places I'd go to where T-Mobile was leasing coverage the signal would drop to flat nothing. I'd have to turn the phone off and back on again to get it to join the new network and then I'd have full strength signal again.
So IMHO, they all have their problems. Pay yer $$$ and take yer choice.