T-Mobile is good, and they are ahead of the game with their plans while everyone else plays catch up. They have a lease program I got where you can swap out your phone 3 times per year so you always have whatever device you want.
As for phones the only choices would be the iPhone, S6, or the G4, but that's just my opinion. LG is working on a new flagship to replace the "G" line, so I'm waiting to see how that looks..