I have used quite a few companies. However, you need to take in account that mergers have created compleately different companies from six to eight years ago. Recently, my wife and I have used Sprint and Verizon. In my own opinion, Sprint beats it hands down. The pricing is better (especially if you look at texting or internet usage) and there customer service was great. I dealt with them on multiple occassions for two years and had no complaints on how they handled it. For the past year, I have used only Verizon. The only benefit I found was the in network. Nearly every friend I have used verizon. My DSL, home phone, and cellular are all verizon now. On multiple times, it took over twenty minutes of hold and two to three call backs to clear up there mistakes. It took three months to get them to correct a constant roaming charge on a nation wide contract. That was very annoying. As for coverage, it is all going to deepend on your area. Verizon has the largest coverage, but the sprint nation wide coverage seemed to be better. I traveled from Indiana to michigan. My honeymoon was in the virgin islands. Sprint had service in every area that verizon did and surpassed them in the virgin islands and upper michigan. In fact, verizon wouldn't hold a signa in almost all of michigan. I had two verizon phones and one sprint. The sprint very rarely went out. Needless to say, when my contract is up I will go back to sprint.
I nearly forgot to mention the phones. No matter what company you use, pay for a better phone. Every free phone with all companies had poor reception compared to higher end models.