My first Android phone was a Nexus, but I moved to Motorola because they were an American company, a Google company, and had some neat bells and whistles added to a predominantly pure version of Android. As Motorola is now just another Chinese/Korean/Taiwanese/etc. entity cranking out Android devices, in hindsight, I regret the decision moving to them for my last two phones. Their software additions were initially quirky at best, and my memories are full of things that never worked quite right. A number of questionable design decisions were also made, and adhered to, regardless of customer feedback.
So now... I am am going back to where I never should have strayed from in the first place... Nexus. Google is an American company, and even though their Nexus phones are built overseas (whose aren't), Google is Android (as Apple is iOS), and as long as I continue to be an Android user, I prefer to support the mothership. They are the only ones that have Android's best interest at heart. It is no longer about bells, whistles, leather and wood, but more of having things work as well as they can, and addressed as quickly as possible when they don't.
Unfortunately, the Nexus has never been a mainstream phone, mostly because it was never offered by carriers. But how we buy our phones has begun to change, and maybe everyone that cares about updates should support the mothership as well to ensure the Nexus program continues. For if it does not, I would consider going back to Apple.