I know I'm kinda in the wrong forum for this, but I just thought I'd share my experience with the 6P. I bought it 2 Fridays ago and returned it this morning.
I love android and customizing my phones. In fact, while I was waiting for my phone to arrive, I wrote a script to automate rooting, decrypting, installing twrp, and transferring a folder full of ROM zips I wanted to test out. I loved the screen of the nexus so much. That amoled display, while not exactly accurate with my settings, really made colors pop and look vibrant. However, battery life was pretty bad compared to my iPhone 6S plus. And apps would reload much more than on my iPhone (and I did do a comparison between the two with the same apps, iOS kept more in the background loaded). I do miss the colorful look of material design and the ease of now on tap, but iOS is working fine for me meets my needs. I'll probably buy the next nexus to satisfy my addiction to messing around with phones and software (spending hours editing that mixer paths file to get the exact perfect volume output for my aux cord for example) and then return it also when I start missing iOS again. Idk I guess android just doesn't suit me very well despite how much fun I have using it.
As for case use, my phone is always uncovered. I don't think I've ever used a case for more than a week.