Based on what we're seeing here, there might be a viable competitor to the iPhone in this space, but that hasn't really been the case until now.
Let's stop perpetuating this falsehood. Agreed that iPhones produce great results. But as you can see from the previous and current DxOMark results, there have been several cameras that had better image quality than the iPhone. High end Samsung and Sony cameras have been consistently good for a while.
Looking at any sort of comparative review, you'll find that on some shots the Samsung produces better results; on others, an iPhone looks better. Each phone may perform a little differently in different situations -- low light, high contrast, whatever. But taken as a whole, at least some Android flagships' cameras have been as good as the iPhone's for a couple of years now.
Nexus phones have been noticeably worse, but they've also tended to cost 60% as much, so it's not exactly an easy comparison to make.
what do you think of nexus 5x in that regard?
The Nexus 5X's camera also kills the Nexus 5's. Nexus 5's camera was poor.