@boblaw0 @askandroid LineageOS gets my recommend.

I've been a long time user (since way back when it was still called CyanogenMod!) and, although I had installed gapps on my devices, the official releases come degoogled by default. They also include many in-house FOSS alternatives to Google's core apps which are otherwise missing on stock AOSP (like the Eleven music player, Jelly browser, etc) so it can be 100% used out of the box without any kind of gapp package installed