Go with the 6S+ you won't be disappointed... However, if your phone comes on iOS 9 keep it there until the 10 update gets a few bug fixes. I think of the 7 as a lateral move instead of an upgrade. It's different for the sake of being different, but the 6S/+ out perform it in some tests and even blow it away in others.
Haven't heard the 6s blowing away the 7 in test. You have a link for that?