I'm pretty much in the same boat. I've been using iOS 10 for the last couple of days and it has really left me with a "meh" feeling. It's pretty much more of the same. Nothing I HAVE to have. And the iPhone 7 rumors don't leave me too excited at this point. I'm thinking about using an HTC 10 and wait for the next Nexii phones. Android seems like it's moving in a better direction for me right now, as a whole.
Yeah knowing that I will be getting iOS 10 on my SE & iPhone 6S+ and the relative incremental hardware change that iPhone 7 represents just isn't selling me on spending €950 again.
I have no issues with things like speed / performance or ram issues - they are still up there with the newest 2016 android devices in day to day usage. Likewise the camera is still holding strong. The 1080p 401ppi screen is bright, clear and sharp on the 6S+ and holds up as well the best on Android despite 2k resolutions. (2k AMOLED 580ppi screens by factoring in the Pentile array is actually closer to 400 affective ppi anyway)
No the biggest things needed are for the 4.7" iPhone.
Significantly better battery life
A step upwards in resolution from 326 ppi to somewhere above 400 ppi
Camera hardware stabilisation
Oh and no more 16gb ever again.
I'm sure we will see an end to 16gb iPhones, and perhaps camera OIS stabilisation on all models - but I'm not sure by making it thinner we will see any battery life improvements or likewise a screen resolution increase in the smaller or larger device.
So it's just your usual updated CPU and possibly ram, and cameras alongside a thinner chassis - at the expense of the headphone jack and likely why we see a bigger camera hump (if device is thinner the hump may have grown which explains the new shaped hump).
Just nothing to me that's worth upgrading for this year.