I suppose if it's not a Pixel device, I'd say LineageOS.

The e/os Advanced Privacy feature is very nice, great way to see which apps have tracker whilst blocking them. Same as running DNS filters but built in experience, easy to view

In itself LOS is fantastic but needs be combined with something like reThinkDNS or another DNS filtering option

Rethink on LOS is fantastic, in particular if you can do the whitelist method - block everything by default, and permit only that which you approve. Takes some time & effort but great control is the reward

I prefer layers, example LOS w/rethink DNS all going thru Control D or NextDNS with Hagezi lists enabled

Overkill? Perhaps , but I love the reporting , helps in learning what's going on, and apps/sites to be avoided

I've come across an article recently that mentions both (and others), it might interest you:

https://blog.gridranger.dev/mobile-oses-featuring-fairphone-5/

Opinions don't matter. Just check how updated they are. This impacts security and thus privacy.

eOS to lineageOS is like Ubuntu to Debian; a more newb-oriented solution with some stuff preinstalled but with less choices; e.g. you can't switch out the iOS-like launcher. if you know your way around, you're wasting your time with eOS. but if it's for a less technically adept user, you might be doing them a favor with eOS. the murena suite can be opted out of.