All carriers have billing issues. All carriers have good stores and bad stores. Choosing a carrier is like voting for a President: take the lesser of evils. I've had Sprint, AT&T Wireless (Cingular), T-Mobile, VoiceStream, Cellular One, Verizon....they all sucked in some way. I put up with Sprint for many reasons:
1) SERO
2) The closest store to my house has very good and easily swayable reps.
3) EVDO Rev.A
4) SERO
5) Uber-current devices.....for the US anyway.
6) Yellow is WAY better than pink or orange...
7) Oh yeah....and SERO
Good luck....