MY family has been with AT&T forever pretty much. Lol.
I have a friend on t-mobile, and he never has reception, misses calls all the time, and gets text days later. Lol.

I have a family plan, we have like 1400 minutes for 5 lines (roll over is nice too) + free calls to any AT&T phones, nights, weekends, + unlimited text, and we pay under $200 for it all after taxes.
Most ppl we know have AT&T, and plus we do a lot of calling amongst each other which = free. 1400 might not seem like a lot for 5 lines, but it's plenty when you have the other perks.