LineageOS, the project sprung from the death of CyanogenMod late last year, has just passed one million users. The community-driven ROM provides a near-stock Android experience and it’s receiving support for more devices all the time: it has doubled its usage numbers in the last month alone.
Of the devices running it, the OnePlus One is currently the most popular, with the OnePlus 3/OnePlus 3T occupying the second spot. The OnePlus prevalence here is thanks in part to its general approach to modding; OnePlus lets you root or unlock your device bootloader (necessary to run custom ROMs) without voiding your device warranty.
But OnePlus also has ties to the Cyanogen Inc. team, having partnered with the company for the software on its original phone. OnePlus later allowed users to choose which software they’d prefer to run on the OnePlus One — its own OxygenOS or the original Cyanogen variant — after breaking up with the company. Flashing ROMs has been a core part of the OnePlus experience for some users and you can read why we feel that OnePlus might have overtaken the Nexus in this vein at the link.
The third most popular device running LineageOS is the i9300, also known as the Samsung Galaxy S3, released in 2012. The community continues to dispel the myth of the two-year lifespan.