Last year I was torn between the 6 and 6 plus. I did the cardboard cutout thing and everything trying to decide. Finally settled on the 6 plus. I do miss the convenience of smaller phone, 4s and 5s. But when upgrading this year was an easy choice going with the 6s plus.
The screen size, 1080hp and super battery life were thing I couldn't give up, once I had experienced them. With 4s I had to get a battery case to last me the whole day. The 6 plus always made it home with reserve. I found I could not go without a case for the 6 plus, as it was too slippery for me. The Apple black leather case solved that for me. One handed use is natural for me now with the leather cased 6 plus.
The black case held up extremely well, looks brand new after full year of use and has been moved to the 6s plus without issues. Saved $50 bucks for a change. Desired to go another year with black face. With black case it's a look I have not yet tired of. Have had both black and white faced phones. Think the seven will be a white face. It's nice to change every so often.
I pocket the plus, jeans, shirt pocket, and suit coat. also find myself carrying it in hand more than the smaller phones before. I reserve one pants pocket for just the phone, shake it out weekly in case I pick up any sand and keep the micro fiber cloth in same pocket. The only place I notice the slightly heavier 6s plus is in shirt pocket. In the hand I rather like the slightly heavier feel.
3D Touch is quickly becoming natural. So much so that I miss it on my iPad Air 2. I use it over the home button more and more. Learning to navigate minus home button as I believe it will diasappear with the 7. Finger print ID becoming part of main screen. Only reason I have for this is a feeling as the last two software and now hardware have been offering more and more alternate commands to the home button. I think Apple is training us, so once the home button disappears it won't be such a huge transition.
I can see physical size height and width of phone being slightly reduced, smaller bezels with same screen sizes. And of course thinner, LOL, ever thinner. My 6s plus has settled down after an easy setup. Battery life is better than my 6 plus. I did a zero to 100 percent charge and got 36 hour standby with 18 hour use. Listening to Apple Music constantly. Uploaded 250 CDs everything I have and enrolled in Apple Music also keeping match subscription as that maintains my clean ownership of my CDs. Nice to have 30 million songs on hand via Apple Music and the cloud. Grooving on German schlager music, Andrea Berg as I write this.
Everyone enjoy your choices 6s, 6s Plus, other phones. Kids growing up today won't have a memory of the before smart phone time. Seems amazing to me. Part of my youth were dreams of having a communicator from watching Star Trek.