I'm going to go against the grain here.
Rumors point to the 7/6SS being incremental at best, and losing the headphone jack.
If you need a phone today, get a phone today. Waiting is stupid, as there's always something better around the turn. A couple months after the 7 drops it'll be "well, you could just wait for the 7S/8, it'll be way better!".
On another point, if you use the headphone jack, get the 6S/Plus. I use mine daily, and don't plan on giving it up or being forced into some stupid adapter like MacBook users have been.
As a last point, with a new iPhone release coming up, you can get great deals on the current gen. Both used and through carriers. Whether it's a BOGO sale at a carrier, or a big cut on a like new one on Swappa. I saved about $400 on my 128GB 6S Plus, and I'd rather have that money in my pocket and a headphone jack than be on the bleeding edge.