I gotta say, both my father and my partner are experiencing software issues with their Pixel and Nexus 5X, respectively.
On the Pixel, he says random freezes/hangups and forced closed apps.
On the 5X, even worse. Random reboots, failure to launch camera sometimes or in general camera lags dramatically, keyboard lag and hangups (they do use different language keyboards if that's worth mentioning), and a few other miscellaneous issues, including rebooting while on a phone call. Incredibly frustrating.
It's particularly frustratingly for me in the sense that I've promised them this is the cream of the crop of Android software. And here I am with my S8 not having really any of these issues.
I'm just not sure why stock is so praised. I get the updates advantage, but all the claims of speed and how it's the best/only form of Android that's worthwhile, just doesn't live up to the hype. Not even in my own experience -- when I had the Pixel myself, I experienced random reboots, too. If you look back at the Nexus/Pixel thread, I spoke about it.
Of course, having said that, it's great that there are options in the Android space. Everybody can be happy.