Salloum wroteI would take the Nexus 6P before the Z5 Premium any day of the week. Stock Android, better speakers, better display (I know Z5P is 4K but it only works in Gallery, other times its 1080p), better battery life and better design (just my opinion)
My opinion since you people explained yours:
1- stock android is more of a downgrade in my opinion nowadays. Custom UIs bring way more features and convenience. Just imagine that people are excited to get multiwindow in android N while I had that on my samsung 4 years ago! Or that doze that sony does way better in their stamina mode... and the list continues...
And custom UIs run as good and smooth as stock nowadays... so old nexus days are gone...
2- better speakers? Maybe... But z5p is waterproof which is more convenient... You'll know that once you drop it in water...
3- better display? I personally hate amoleds and would take LCD anyday. QHD is the biggest lie/gimmick. FHD is more than enough for me/in my opinion.
4- better battery life!? Of course not! Not by an inch, nor by a mile! Running on FHD most of the time, and continuing sony's trend (and 3450mah), it's much better on the sony! Turn that stamina mode and get miracles!
5- better design! I agree on that one! I hate sony's design!