There are tradeoffs with any phone. All phones have different strengths and weaknesses when it comes to design, sound/speaker quality, battery life, storage options, screen quality, size, additional features like stylus/pen support, UI customizations, etc and not everything is a matter of highest number on spec sheets but preference.
The Moto X Pure looks like I solid phone - I don't own one, so I can't say if it would be my favorite or not - but people prioritize different things. Just looking at recent threads like talking about plastic versus aluminum, it's not going to be a single answer for what's best.
Some of the biggest discussion threads in this forum in the past have been about things like the presence or lack of microSD, removable battery, whether the phone in questions ships with stock Android or not... some of these issues determine whether some users will even consider buying a phone or not.
I just bought a Nexus 5X, but I did consider the Pure. The Nexus 5X seemed like a better value to me at $300, and if the Moto X Play (for battery life) were available at the same price here I probably would have bought that. Technically it's available in the U.S. as the Droid Maxx 2 on Verizon, but I'm on Sprint and it was easier and cheaper to get the Nexus 5X.