But the update experience on flagships (except if you count the Nexus 6P) is absolutely terrible. I had an Android excursion: Nexus 4 -> Moto X 2013 -> Moto X 2014. Motorola was known at the time for quick updates. This meant in practice that they pushed out an extremely buggy Android 5.0 quickly, and then waited half a year to push out a release with fixes. On the Moto X 2013 I had to wait more than a year (!) for Lollipop, although at the time of release the phone was only released a year ago.

tl;dr Android updates on non-Nexus flagships are terrible. Updates are typically months late and stop after 12 or 18 months.