I'm really impressed with how far T-mobile has come in the last few years. I was hesitant to switch to their service because they used to have a pretty weak reputation, but now their coverage is fine.
On top of that, they offer non subsidized cell service, so the monthly rate is really low as long as you buy your own phone. Today I realized that they even allow free tethering so you can use your cell phone as an access point for your tablet or laptop.
Those were the biggest complaints I had about the other carriers, so now I'm sold on T-mobile.