Tmobile mainly because I use their home internet service which is actually very good in my experience, hell I even use it to play online games and never felt any lag. I pay $120 for unlimited service for my phone + home and never felt the need to switch for now. Oh and they also offer a yearly free MLB subscription on the side which is awesome.
Microsoft is a pathetic little husk of a company, what a corny and predatory practice that not even google cares to do if you search other search engines.