It is better to go with the Google Pixel now, however, it is a high-end premium handset and caters to that niche. Google is no longer focusing on affordable Android experience that it intended with Nexus series but is taking the competition straight to the likes of Apple. When you are considering top-notch specifications but also save up on budget, Nexus 5X makes sense, however, if budget is not a constraint you should prefer Google Pixel over Nexus 6P, any day. Also, factor this that while Google Pixel will be the first in line for any Android feature or update in future, Nexus line will become obsolete very soon. For starters, Google Pixel has the best camera in the industry right now, it has the best integration with Google services at the moment and also comes with Android Nougat 7.1 straight out of the box. Also, Android Nougat goodies like Pixel Launcher and Google Assistant are exclusive only to the Pixel lineup, and they are huge benefits to have. Moreover, the tight integration between the software and hardware, makes Google Pixel better than all existing Android devices out there at this point.