Well, it's been a long time coming, but the below post sums up my personal experiences -- as objectively as possible -- with the top three mobile carriers in my area. I've used them all for a few months now (in my home market of Oklahoma City and while traveling) and have come to a conclusion and a rating for each. Whether you agree or disagree, drop a comment and let me know your experiences. Note: the post below is more tilted from a "personal" use angle rather than a "business" use angle -- but I have used all these services for both personal reasons and for small-business reasons. I'll be summarizing both voice and data features from a handset perspective -- no datacards or heavy data use stuff this time.
Carriers used:
Cingular Wireless
Sprint Nextel
T-Mobile
Java applications used:
Opera Mini
Gmail Mobile
TeleNav
Here we go...
Cingular Wireless: decent amount of handsets (wish there were more with HSDPA speeds) and very good coverage. However, HSDPA was still not available on my home market (which is a smaller one), and EDGE just does not cut it, even for handset browsing and such where a lot of data is involved or picture messaging is used. Regular prices for voice are competitive, as I used the 450 minutes/$39.99 a month plan. Data services are a little pricey for the actual value, as MEdia Works for $19.99 -- which comes with an SMS bundle -- still does not give unlimited data. Yikes. Also, forcing some of Cingular's handsets to "roaming" on the fringe of Cingular coverage was an exercise in frustration (just like T-Mobile...see below). Used the Samsung SYNC and the Cingular 8525 handsets. Customer service hold times were LONG when I called, but the help was generally good (but far from great). Hours very goofy (closed past 9pm?) and email customer support was useless (canned replies that were not helpful to specific questions).
Sprint Nextel: decent handsets -- and many now feature EV-DO Rev. 0 speeds direct from the handset. Where I live and travel, coverage has been excellent (as was Cingular's coverage). No dropped calls at all. The ability of Sprint to allow a customer to "force" their handsets into roaming was crucial for me, as several times -- when I knew I was traveling outside Sprint's coverage or working on the fringe of coverage -- I could tell the handsets I used to lock onto roaming coverage (which was included in my plan) and continue using voice and text messages (some handsets can do roaming SMS and data -- some cannot). Sprint's price of $15 for unlimited EV-DO handset-based data was fantastic -- by far the best value for the money with data speeds being the top factor. Add another $5 for 200 SMS messages and I was at the same $20 as Cingular, but with a reversal of services (less text messages but unlimited data). Used the Sanyo SCP-8400 and the Samsung M610 handsets. Although Sprint has a bad rep for atrocious customer service, I had zero problems with them. Phone calls were answered in a few minutes and reps were very helpful when I called. Email customer support was superb -- email responses came back generally within 18-24 hours and were filled by a nice salutation and a closing (just like any business reply should). There were no "canned answers" here -- *all* email responses from Sprint were filled with detailed answers to my questions (some pretty in-depth) and I was extremely impressed with Sprint's ability to answer email questions with a single contact. Not sure where Sprint's bad rep in support comes from -- my experience was the opposite.
T-Mobile: decent handsets, but both Cingular and Sprint have a better and more varied selection (as opposed to sheer volume of handset selection where all have similar features). T-Mobile's voice minute prices were the best by far, but you pay for that in lack of coverage. T-Mobile has, though, greatly expanded its coverage with roaming agreements with Cingular (on the GSM850 band), so this was a concern that is being rectified every month I think. I had a large amount of issues when I was on the fringe of T-Mobile's network (with a bare signal not good enough for making a call or using EDGE data), since I could never "force" the handsets I used to lock on to a roaming signal (Cingular in most cases). This inability rendered the phone basically useless when on the fringe of T-Mobile's coverage. By far, Sprint's solution of allowing the customer to actually choose "Roaming" was the winner here -- this feature alone was crucial to me several times. T-Mobile's nationwide EDGE network -- no 3G yet -- was slow and it showed. However, $5.99 for unlimited handset-based browsing was the cheaper deal here -- but of course, T-Mobile blocks certain ports for that and I had trouble with some java apps accessing the Internet with that "T-MobileWeb" $5.99 plan. Sigh. SMS rates were good as well, as $5 got me 400 messages of any type -- text, video, picture or IM. Handsets used included the Samsung Trace and the Motorola RAZR V3t (same as the V3i). Customer support was also top-notch -- the reps on the phone were incredibly helpful and went what I considered "above and beyond" to find answers to my in-depth questions every time. Email support was not as good as Sprint's exemplary service, but was very good nonetheless -- and miles ahead of Cingular's canned replies and limited hours (and LONG response time).
All in all, the best combination of voice pricing, data features and pricing, messaging pricing, overall coverage, handset selection with advanced features and overall technology experience and customer support experience was Sprint -- by a pretty decent margin over T-Mobile and Cingular.
By the way -- the coolest handset I used during this process was -- by far -- the Samsung M610 from Sprint. The Cingular Samsung SYNC was a pretty close second. The T-Mobile RAZR V3t seemed like a dinosaur by comparison to both the SYNC and the M610 (although the Trace was pretty cool and slim). The M610 is a marvel though -- and was just the most fun to use.
Note: the way I chose to evaluate pricing, features, coverage and certain aspects of service more important to my usage patterns -- of course -- will be different than with many of you (no flames please!). I am anxious to hear your replies to this thread though -- what experiences have you had?

1. A longtime Sprint customer, I just recently started taking advantage of their $15 unlimited data plan. When you combine it with Java apps like Gmail, Google Maps and Opera mini, you get great functionality without breaking the bank. Now I have even more reason to swear by Sprint.
Posted at 5:34PM on Jan 23rd 2007 by EJ