Wait for New Android Devices
If you aren't married to the iPhone you should know that there are a few Android flagships on the way as well.
The Samsung Galaxy S20 isn't official, but all signs point to an arrival in February ahead of the Apple's Q1 launch window.
The Galaxy S20 should improve on the foundation set by the Galaxy S10 series so it might be worth it to wait and compare it to the iPhone 6s Plus and other iPhone models.
If you don't need a new phone right away, think about waiting for Samsung to make its announcements. They should come next month.