LOL, such brand loyalty...
I started with AT&T back in the dark ages: 1998. Then AT&T left town, trading with Sprint so they could corner the market in some other region.
I stuck with Sprint for something like fifteen years, at the end only because I was in a legacy unlimited family plan.
Coverage in my neck of the woods sucked, but...
Then I got fed up with their purchasing system and went shopping. AT&T was back, but the only way I could get a decent deal is if I bundled a bunch of crap I didn't need (either way, it would have cost me a bundle). I ended up with Verizon, got me five new phones for next to nothing, added a line, and still ended up paying less than what I was paying with Sprint.
So now I am I Verizon until the end of this year at least. I'm in a new region now, so maybe ill change again.
Here's the thing: every market is different, just like every customer is different. Different demographics, different needs and requirements... No one company is going to satisfy everyone, and for the most part, they are all interchangeable. Until there is only one game in town. Then you are paying out the nose for crappy equipment and crappy service.