Galaxy nexus, while plastic, was still very nice phone.

Nexus 5 had already quality issues. Pixels went downhill completely, while simultaneously bumping up the price.

The Nexus One was built by HTC. The Galaxy Nexus was built by Samsung. The Nexus 5 was built by LG. Pixel is in house, of course, but IIRC, Google bought a fragment of HTC some time ago.