To me, I don't see anything interesting about the 6 and 6+ that would make it worth jumping from an iPhone 5S or even an iPhone 5.
MUCH BETTER BATTERY LIFE = 6+ battery is over twice as large as iPhone 5s battery, from 1,440 mAh to 2,915 mAh. While some might say "battery life will be the same because of the larger screen" it's been shown in iPad's that is not true, devices like the Mini have an enormous battery life despite the 8" screen and only a 4,490 mAh battery. If the 6+ can get just half the battery life of the Mini that will be a huge improvement from the battery life of the 5s. Apple is already reporting the 6+ will provide several hours more battery life than the 5s.
LARGER SCREEN = no dispute there
FINGERPRINT = 5s had fingerprint but 5 did not. That will make it much easier to unlock the phone and make iTunes payments
NFC = if mobile payments work out like they're saying this could be the best feature of the iPhone 6. It could mean never needing to get out your wallet and never having to worry about your credit card or identity stolen.
OPTICAL IMAGE STABILIZATION = would help a lot when recording videos, optical image stabilization is usually much better than digital stabilization.
BETTER CAMERA = anyone that has bought a cheap camera knows big megapixel numbers do not mean a good camera. The iPhone 6 is still "only" 8 megapixels but adds a new iSight sensor and Focus Pixels technology for focusing faster.
MOTION CO-PROCESSOR = anyone that uses their phone while working out would like this. The A8 chip includes the new M8 motion co-processor which recognizes data from gyroscopes, accelerometers and compasses.