Stock Android is likely to be better than anything oems will modify it to be.
Urgh, why aren't there any modern 4/4.5" Nexus phones. :(
I've had my 5x for months and only come across a couple of bugs, a couple of times- but they happened once and weren't reproducible.
It didn't work correctly and there were no new Nexus devices smaller than 5".
It's the first time in my life I've gone in early and bought a phone in cash off contract. I've not had an Android since.
Something similar would happens to Android world if people came to recognize that all phones' software were equal. It would lead to a race to the bottom in price terms.
Also, good lord Samsung's UX is just plain ugly. Everything about it, including layouts, color schemes, etc., makes me feel queasy. Their design aesthetic is why I go out of my way to avoid everything they make.
Google has no process in place how to support their customers if an OEM breaches contract.
They're hardware vendors trying to compete on software. How about trying to compete on hardware?
Stock Android UX is average at best. It is too complicated and disorganized for ordinary people, and there is a lot of room for improvement.