What about TING for the win?
Buy in at $0 per month + $6 dollars per phone, and then get charged according to use. Their data pricing might make stand alones a little better than family for a data family family, and they don't have the latest phones (yet), but this is the model we have all been begging for!
If I weren't on a now-defunct Tmobile no contract 1500 min, 5GBx2, unlimited text, +1 dumb phone plan for $120, I'd be all over Ting.
Proprietary phones FTL. I do not really give a crap about any prepaid carrier where you can't bring an existing phone. Why should I have to waste a bunch of money buying an overpriced, outdated phone BRAND NEW that can't be moved to any other carrier when I already have a perfectly good phone right now?
Basically, Sprint MVNOs are out. All of them require proprietary phones. You can't use a Sprint phone on Virgin Mobile, you can't use a Virgin Mobile phone on Ting, you can't even bring a Net10 Sprint phone over to Straight Talk even though both of those carriers are owned by the same company! Besides, the Sprint network is utter ass; there have been many times when I'm outside the range of Wimax where I have just given up on trying to use my data because it's so slow as to be unusable. And I feel like a chump paying what I do for data access that I can't even use!
Verizon has one MVNO that offers bring your own device - Page Plus. The rates are a bit high and the caps are low if you want data, but I guess that's the price you pay. It's still much cheaper than Verizon postpaid.
Other than that there's pretty much T-Mobile and Straight Talk. Straight Talk are shady as all get out, advertising "unlimited data" but then canceling people's accounts when they exceed some secret data limit that they refuse to tell you about. Kind of ironic given their name. So T-Mobile is really the only wireless carrier out there that doesn't hate their customers.