What's wrong with sprint? AT&T won't allow you to unlock Bootloader even on phones that allow it like the HTC One. Verizon has good service but they get none of the Nexus phones now because they are CDMA. I know you can unlock the VZW HTC One and their Samsung phones.
I read in a few places that you can just put an AT&T sim in a N5 and it will work with their service. That is expensive though because you get no contract discount on the phone. I paid $106 dollars to Sprint yesterday and have a $50 gift card on the way. A N5 from the play store is $350/$400.
Sprint is garbage near me... I rarely get service and the data speeds are still slower than dial-up... I NEED to have the zerolemon battery on my GS3 or else the battery dies in 5 hours due to it always searching for signal. -___-
And I thought Verizon was the company not allowing you to unlock the bootloader... at least that was the case for the S3...