Unsure about which carrier to get an iPhone 5S from? On-contract or contract-free? Apple simplified it all, by offering its latest premium handset on the Apple Store, where from a centralized location, you can pick the right trim, capacity, network, and plan.
On-contract, the 16 GB variant is priced at $199, 32 GB for $299, and 64 GB for $399. These prices are kept uniform between AT&T, Sprint, and Verizon, and don't change with trims (black, silver, and champagne).
The only carrier offering the iPhone contract-free is T-Mobile, at $649 for 16 GB, $749 for 32 GB, and $849 for 64 GB. The handset reaches you with a T-Mobile connection, which you can then request the carrier to unshackle for free.