I think if camera and battery is a main priority for you, then the Nexus line isn't for you based on their track record. Every Nexus phone has had issues in some areas esp camera and battery life. Even the Nexus One made in Taiwan by HTC had the power button and wonky touchscreen issues. With collaboration comes risk. Google's Nexus products are really catered for the budget conscious who needs to accept some compromises for its price. But getting a top SoC for generally $200 less than others, faster updates, and no carrier or OEM bloatware still makes it the best bang for your buck "flagship" line. Just remember five generations of Nexus phones has been released and not one of them had a great camera or great battery life.
I think OEM's will never provide the best components and features for a Nexus phone. They save some of the best stuff for themselves. If Google wants to make the best Nexus phone with the best components and features, it has to be manufactured by Google themselves. Not rely on partners who basically make a stripped down version of their flagship phone. But obviously Google doesn't want to directly compete and scare away their partners. Ad/online service/software company is what Google really is. Google just wants us to be online, click an ad, and use their services. They could care less selling hardware. They sell Android to us and to manufacturers which is FREE and OPEN to use. ChromePixel and Google Glass aside, Google never has looked itself as a hardware company.