Relatively low prices and a wide-open attitude towards user customization make OnePlus phones popular with the ROM crowd. They're getting a big boon today, as official CyanogenMod support comes to the smaller, cheaper OnePlus X. The X is equipped with the custom Oxygen OS, but for those who prefer the community-built ROM, CM13 is now available in nightly build flavor. The first release is up on CyanogenMod's download page right now.
The OnePlus X is fairly close to AOSP code as it is, with only a few custom OnePlus apps and a few interface tweaks in the software (which was at least partially developed by former Paranoid Android team members). Even so, there are a couple of advantages to switching to the CyanogenMod side of the tracks, particularly the speed of updates. Oxygen still hasn't been updated to Marshmallow code, except for a beta available on the OnePlus 2. CyanogenMod 13 is based on Android 6.0, plus the various tweaks and customizations built by the CM team.
If you rely on your OnePlus X as a "daily driver" phone you might not want to flash the very first nightly. Usually there are a few kinks that need to be worked out over a month or two. But if you like to live dangerously, Team Win recovery is available for the X, and there's a Marshmallow version of Gapps for flashing the Play Store and Google services.
- CM download page