I have a Nexus 6. Google's services are top notch and stock Android is blazing fast. All but one of my friends have iPhones now, which gets really annoying with iMessage. But Apple's services are woefully inferior to Google's in my opinion. The N6 was my first Nexus phone and from a software perspective, I've enjoyed every minute of it. From a hardware perspective, the N6 has been a disappointment I will admit. I loved it for the first three months, but the phone is unwieldy. I don't have small hands and still find it pretty difficult to hold when taking photos; using in the car; or doing stuff on the go. Also the camera on the N6 is quite disappointing. The front-facing camera is grainy and almost unusable; the rear-facing camera is a non-starter in low light; and the constant readjusting and focusing required to get a good shot makes the camera's speed negligible.
Honestly, I was prepared to sit out this year, but I am very impressed by the 6P. Fingerprint-reading technology, a camera that addresses all of these issues, a better front-facing camera, and better battery performance are all on my list. And I mean, the 6P is gorgeous. I also love the Nexus brand and I want Google to continue evolving it, so I'm willing to give them my money. Nexus moves Android forward and makes Android better.