Although it may be unpopular, I use Tracphone. We have few options out here in the rural area, and Tracphone is one that is available for us. I actually like it because there are a variety of plans and phones available and, you can get service literally everywhere. This is one of the best things about being able to use this network. i find it to be one that is very useful no matter where you are.
T-Mobile. While I'm not a fan of their stance with Net-Neutrality and the like, they're really is not much of an option in my area. That being said, there service isn't bad and they have the right prices for phones. Still it would be nice to have coverage in more area.