In the past 6 months I have had, for varying reasons, three different cell phones with three different carriers. My thoughts on each along various criteria…

Coverage and Service – far and away the most important criteria. The damn thing’s gotta work to be useful

• Cingular – Utter and complete crap. It was always a mystery whether or not my phone would work when I pulled it out. Secondly, this GSM phone took the longest time to find a signal (5-20 seconds compared to <5 seconds for TDMA and CDMA). Finally, SMS was regularly dropped silently – was not a reliable medium.
• AT&T – AT&T’s TDMA coverage is excellent. However, from what I understand, the GSM coverage, while being a shade better than Cingular’s GSM, is still far from ideal – Basically, GSM in the United States is not ready for prime time. Additionally, they have done the best job of creating interesting content and services (american idol voting over SMS, 411 over SMS) – granted when I say interesting, it is not interesting to me, but they are definitely trying.
• Verizon – Far and away the best service coverage, both in terms of quality and area covered. I never have to worry whether or not my phone will work no matter where I am. However the lack of full international SMS is a little annoying.

Customer Service – at the end of the day the bar is usually set pretty low on this so any improvement is immediately noticeable

• Cingular – Like pulling teeth, customer service people consistently lacking in knowledge. Secondly, their billing system is flaky requiring even more calls into customer service. Finally, switching from a national plan to a local plan (or vice versa) resets your service contract (essentially adds a year to it).
• AT&T – Fantastic. Customer service people friendly and helpful and most importantly, knowledgeable. I have had a couple of non-trivial billing issues, all of which were solved quickly and efficiently. Additionally, price plans changes are made effective for that entire billing cycle, not prorated from that point forward.
• Verizon – Most of the time they are really friendly and want to be helpful, but tend to lack in higher end brain functions. I find that even simple tasks, even though they eventually always get solved, always take a *loooong* time.

Phones

• Cingular – Not bad actually, but does it really matter – with coverage this bad, you never can use the damn thing.
• AT&T – While there is a good selection of GSM phones, the TDMA and GAIT (combined TDMA and GSM) phones are lame.
• Verizon – Definitely improving, especially on the high-end.

In summary

• Cingular insults you across the board with bad marks in everything. I will give them credit that they are trying the hardest, offering features like nights that start at 7 and rollover minutes, but then again, they need to because they really need the most help.
• While AT&T‘s TDMA coverage is fantastic, it limits you to a selection of really lame phones and no GPRS/advanced data services. Since the GSM coverage is not acceptable, it means that it is not possible to get good coverage, data services and a cool phone all at the same time.
• Verizon‘s excellent coverage and a kick ass phone makes it the best carrier of the bunch.

Some thoughts on the other three national cell carriers in the U.S….

• T*Mobile/Voicestream – Tie up with wi-fi hot spots is possibly compelling, but still limits you to GSM coverage. Cingular and T*Mobile tend to share towers so the crappy Cingular service you get in the Bay Area is the same crappy service you will get on T*Mobile.
• Nextel – Don’t know much about them except that nobody that I know has service with them. I guess if you are into push-to-talk then it is the carrier of choice.
• Sprint – From what I hear, Sprint is far and away the best value for money in terms of the number of minutes you can get for the price, plus you can get unlimited data for just $10. However, it seems that Sprint’s coverage is pretty rotton. Has one of the better selections of phones though.