Hmm, I have to disagree with the statement of T-Mobile having bad customer services. I have been with many cell phone companies and I end up staying with T-Mobile (4 years now) due to good pricing and more bang for your buck (no additional cost for tethering your phone). I will say that until about 2 years ago the lack of 3G service in my aread (20 miles outside of Baltimore) was bad but service has greatly improved.
I also travel to Puerto Rico to visit my mother-in-law (great service) and down south and the service is great (atleast the data because that's what I'm using 90% of the time).
On a side note, their variety of phones is not always up to par.