I flip flopped a bit. Started with 6, but considered a 6+ for the added features.
Stayed with the 6.
For me, I have 2 teens on my account. They get my leftovers. In return, I get their upgrade eligibilities. And always a new phone in my pocket.
So really I only need to hold onto the 6 for another year. Then I can pass it down... and get the 6S, 7, or whatever they call it.
I feel that day-to-day I would regret having a 6+ if it didn't fit in my pocket, etc... Kind of like my DSLR. Its a big beautiful camera, takes great shots (when I remember to carry it) But all my pics are taken on my iPhone because it is small, portable, and always with me. Too big, and that stuff stays home, kwim?