LineageOS is my current mobile operating system of choice. Here are a few reasons I like it, in order of importance:
Freedom: Lineage OS almost completely free (as in freedom) software, with the exception of the baseband. Unlike iOS or Stock Android, users can read and contribute to the code base. Apple completely controls iOS, while the user controls LineageOS. Google completely controls Stock Android and constantly collects personal information, while the user controls LineageOS and all data sharing.
Economy: LineageOS is based on Android and runs on >185 phone models. Most of these phone models are less expensive than iPhones with comparable features. iOS, however, can only run on Apple devices.
Geekyness: LineageOS, like many Android distributions, offers extreme customizability relative to iOS. Features include system terminal access, a wide selection of app launchers, the ability to install apps from 3rd party sources, and a permissions manager called Privacy Guard.
To get started, head over to the LineageOS website, or for a variant with free-software re-implementations of Google’s proprietary core libraries and services (runs apps that require Google services), check out the MicroG Project.