Conclusion. On a financial basis, T-Mobile wins at every tier, and offers an even better deal if you're willing to bring in your own phone and forgo a contract. T-Mobile also addresses the lack of an iPhone with its own Micro SIM card and ability to serve unlocked iPhones, but that's likely too much of a hassle for most customers. Sprint has a superior lineup, even if its phones can't yet take full advantage of the fastest possible network.
Of course, coverage is the real wild card. Customers in the few Sprint LTE markets that are up will have a superior experience. Coverage on either carrier will vary greatly depending on location, time, interference, and local wireless traffic. By the numbers, T-Mobile offers the best deal, but you should do your homework before committing to either unlimited data option.