some more thoughts about the Nexus 6P after using it for a day or so:
Camera: No noticeable difference between 6s Plus and Nexus, although on a couple of pics the Nexus has thrown up a random greenish shade.
Screen: Colours are better refined on the iphone. This is quite important to me as I watch a LOT of streaming.
BBC IPlayer: This deserves its own section as I download and watch a lot of shows, both Radio and TV. One annoying difference is Background App Refresh is not supported in ios, so when downloading, if screen goes in standby mode, then it stops downloading, and it also stops if you switch apps. Easy(ish) workaround is go in settings and set screen lockout to 'never'.
Android wins here as you just start the download then forget about it.
Touch ID v fingerprint sensor on 6P : both equally just as good. the 6P sensor is in an unusual location and it takes time to get used to. One important thing to note is Touch ID has been around a bit longer, so certain apps like the AMEX one that I use a lot, support Touch ID to log in - big plus for me.
Sky WiFi app: Im not sure why but it doesnt seem to be supported as I can't get it to work on the Nexus. could just be a software glitch, but its not a huge issue. It just means I can't automatically pick up supported wifi hotspots when on the move.
WiFi Calling: supported and works out of the box on the 6s Plus. Not yet supported by my operator (EE) on the Nexus. This is quite useful to me as my cellular reception at home can be rubbish at the best of times and WiFi Calling has been a godsend.
Next I'll play with Google Photos on both IOS and Android and see the major differences
At the moment I'm still edging towards the 6s Plus for now. I'll keep using the Nexus for a couple of more days at least.