LineageOS

I've been using it for about 4 years and looking for a replacement now. While being a breath of a fresh air on the surface, it's poorly implemented in details.

1. Buggy: random hangs, random reboots, even something as basic as receiving calls is routinely getting broken.
2. Major Android version upgrade is just ridiculous: you have to reinstall phone's original ROM first, then update Android version there, then install new LineageOS version.

In general, I feel it's a classic misaligned opensource where devs care more about their appearance as proud opensource guardians more than about actual users.

good alternative to Android

I'm still getting weekly updates on my Oneplus 7 pro.

Lineage is a very vanilla, neutral project to port many devices to an AOSP-based distribution of Android. It doesn't include the bells and whistles of other projects, but that's the point.

Countless other distributions use LineageOS as their starting point, and that's for good reason.

Hands down the best custom ROM I've tried so far. It allows you to install an Android operating system without the usual annoying apps and games that many phone companies tend to add to their commercially distributed Android systems. What I like the most is the option of being able to install the Google Apps by myself, being "Pico" the best option (the lighter version of the GApps). The only disadvantage is that it is necessary to have some advanced knowledge (make backups, root and install a custom recovery bootloader) being that there are also many phone models that are not supported, especially the Sony Xperia M series. There are users who solve this by installing a similar version for a different phone, but this usually produces incompatibilities, such as malfunctions of the front camera, among other various issues.