T-Mobile is quite good in my experience. It took my fiancé like 3 years of crappy Sprint service for her to finally make the jump over. I always had the bars when she didn’t. What’s strange is that I noticed T-Mobile will drop out in the middle of urban areas. Other than that thumbs up.
I'm using both T-Mobile and Sprint. I like the T-Mobile speed. Sprint also has great service. I like have 2 so if one doesn't work in a particular place, the other usually does.