As for the comparison between custom ROMs, you mainly have LineageOS and derivatives like e/OS, iodeOS, and CalyxOS, as well as GrapheneOS which is doing its own thing with Pixels (and future Motorola devices)

Base LineageOS is pretty much stock Android without Google services by default (though you can install microG). e/OS focuses more on the degoogling side of things, and they tie in Murena cloud services + their own iOS-like launcher too. iodeOS is another more privacy-focused spin of Lineage, and they have additional controls on content blocking (advertisements, trackers, that sort of thing), and you can optionally enable parental controls too. CalyxOS is a security-focused Lineage spin, though not to the extent of GrapheneOS. They only recently came back from the dead, but they seem like another good option too!

GrapheneOS is an uber secure version of Android, there's a table online for all the security features that Graphene has over the others, look at those and see if any of them are important to you. They also have a neat feature where apps requiring Google services can be sandboxed and kept separate from the system!

I am moving to Piefed at scallisto@retrofed.com (https://retrofed.com/u/scallisto)