Where can I sell an Iphone 5s for the most money?

I won an Iphone 5s from raffletopia.com and its the second phone I've won on that site so I don't need the second one, where can I sell it for the most money? Craigslist?

I would sell on craigslist, don't open the box though, its worth more if you can say its unopened as that erases all doubt about making sure its not a lost or stolen iphone.

Yes, Craigslist would be the best option. You could also try eBay. Or online buy-back websites.
When selling online, you probably will get less then selling the phone locally or on eBay, but it is practically hassle-free. Check here to get the price reference: http://www.gadgetsalvation.com/sell-iphone.php