It would seem Google has effectively killed its Google Play Edition (GPe) line with the latest device they've taken out. According to PCWorld, the HTC One M8 GPe has been taken out of the Play Store. GPe devices were designed to run stock Android but Google slowly took these out of its digital store. Now, if you want to get a vanilla experience of Android your option is Nexus 5 and Nexus 6, which are both Google-branded phones.
Source: PCWorld