Nexus 5X / 6P if you want it right now, Pixel / XL if you want it a little later. Nexus phones get frequent updates, have a clean un-bloated stock ROM, and a good selection of custom ROMs. The Pixel is the successor to the Nexus line, Google is renaming it solely for marketing reasons. They're trying to sell it to consumers more, rather than selling to devs and hobbyists like the Nexus line, but the Pixel will still have Nexus-tier updates and rootability. Sounds like you're patient so I'd go for the Pixel since it'll have beefier specs.