I started with a 8700c that I had unlocked (insert shameless plug for Adam at gsmphonesource.com here
) for use on T*Mobile due to the quality of the 8700, my past experiences with Cingular not being so good, and T*Mobile's value pricing.
Unfortunately I ended up having to get a 7250 on Verizon due to the fact that I use the phone function heavily (I am a contractor/developer and am in the field all day) so the my primary use is phone with email/data being nice to have, and in my location T*Mobilís voice quality is spotty although I never had a problem with the data portion. Verizon was my prior provider with a Treo 650 (The BlackBerry is so much better but thatís another topic)
That is a long-winded way of saying think about how you are going to use the device then select carrier that best matches that need, then select the best device your chosen carrier has. I look at it like this;
1) Carrier based on - coverage, voice quality, data quality/speed, GSM vs CDMA (world capable vs US limited)
2) Particular Blackberry device based on Ė features needed/wanted
I donít think you can compare the 72xx line of BlackBerry to the 8700. In my opinion the 8700 is far superior. It has a fantastic screen, snappy processor, and with the right network (EDGE) good data speed. The 72xx is fine but I sure would love a 8700 on Verizon. I did keep the 8700 on T*Mobile that I use when traveling internationally .