Google Pixel C
Rather than release a Nexus tablet in 2015, near the end of the year Google released its own tablet that was 100% designed, made and manufactured by Google. It's called the Pixel C, and is designed similar to the Chromebook Pixel lineup. Which means it has amazing quality.
At $499 it's an expensive tablet, but arguably the best Android tablet available. And while reviews were negative for the lack of "productivity" features, considering Google's selling it with an impressive optional keyboard accessory. It by itself, is still an amazing tablet.
It has an all aluminum unibody design, excellent battery life, the same four LED's on back as the Pixel Chromebook that shows battery life. USB Type-C for quick charging, and dual speakers that sound great. If you want one of the best Android tablets, and cost is no concern, look no further than the Pixel C.
As more tablets arrive in 2016, we'll update this list.