TMobile HSPA+ speeds are faster than AT&T but TMobile's coverage is not good outside major metropolitan areas. AT&T's still has good speeds but aren't as good as TMobile but their coverage footprint blows TMobile's away hands down. IMO if you have over 3 MBPS you are good to go. I live in upstate NY away from a major city and I have gotten as much as 9 MBPS down with AT&T. Tmobile's coverage up here is sporadic to nonexistent.
Agree 100%. I'm on my 2nd month now of TMobile prepaid $30 service and while I'm "satisfied" with the service so far, I'm going to try ST AT&T for next month. I'm in the Atlanta area and while my TMobile speeds have been awesome at my house/around town (~12-18MBPS), I get almost zero building penetration at work during the week. I'll get an email notification like twice a day, where I should be getting them like 20 a day, at least. And this is a huge dealbreaker for me. Can't use any data connection hardly.
I know ST AT&T will probably yield slower data speeds, but being able to use my phone for where I am 80% of a 7 day week is more important to me. I love the $30 price and 5GB unlimited data before throttle, where ST has all the "2GB" throttle BS limit, I'll have to try it. Some people say they have no problems with ST, while others do. I'll have to make my own decision.