How long do you plan to keep the car?
Having 18 month of additional warranty may be interesting.
The P85D is very very fast, the 90D is more than fast enough.
Going new and chose the options you want has some value too.
For the same price I would go with the 2016 if the wait is not too long.
We sold our 2014 to get a 2015 D with autopilot. Quality improvements are noticeable. We are really happy that we did upgrade.
You might want to get some insurance quotes as well. When shopping around recently, a friend found insurance for a P85 would've cost him several thousand dollars more per year than a non-P model. The non-P would only be slightly more expensive than his current Ford Fusion.
It has the next gen rear seats. They aren't that bad right?