I love mint. They're owned by T-Mobile but interestingly while I was paying $15/m for mint and my wife was paying $90/m for T-Mobile I often got better reception, especially when we were somewhere spotty like up a mountain. I assumed it was just a difference in phones, but since she switched to mint she says she gets better reception. Completely anecdotal but interesting.
I'm dreading the day they go to shit.