Definitely go with Apple!
Honestly, Apple direct doesn't have any restocking fees on iPhones with the 30 day return period. If something was wrong with the phone, it's so much easier to deal with Apple. Even if you decide 5S features aren't worth it, Apple will take it back.
It's not worth the risk to buy from the carriers with their more stringent return policies. Honestly I want phone on day 1, but Apple store is too hard for me to get to, so I will order with Apple. I have other resellers a short walk or drive away, but I don't want to deal with their policies.
Apple will go out of their way if something isn't quite right.