I'm one of those weirdos that got a 5S after the 6 was out. Played with the iPhone 6, didn't like the size and shape at all, ordered a 32GB 5S. Don't think I'm missing out on any cool feature yet although I'd love me some 3D touch. Some apps don't work too well on the "small" screen (notably the Music and Podcast app are terrible nowadays) and that's probably intentional. :-(
Hoping for an iPhone 7 in a 4" screen size. Preferably natural metal color so it doesn't look terrible after a year of normal wear.
The thickness and weight of the 5S is pretty spot-on, it charges super quick with the right charger and battery life is decent. Just wish the fingerprint sensor was a a bit faster and worked with sweaty fingers. The sleep button rattles a bit (unlike the earlier phones) and I'd like 3D touch and altimeter. I'll take all the camera updates I can get (mostly zooming) as long as it fits in the case.