For the past five or so years I've been using prepaid mvno carriers (in the us btw) and buying my own phone. It's somewhat of a frustrating experience trying to figure out which phones will actually work with which carrier. There's a lot of very attractivly priced phones from Chinese companies that unfortunately just don't support the u.s. LTE bands that i need. Im not really the kind of person who wants to buy a $600+ flagship and carrier offerings are generally abysmal and overpriced.
I also don't feel like I have very many options for carriers as I Live in a fairly rural area where t-mobile gets fairly spotty coverage. I have seen compelling options for Verizon if I wanted 4+ lines (it's only me and the wife right now, so that doesn't help us much) .
I'm definitely jealous of people in Europe and parts of Asia when it comes to cellphone and internet options.