If you care about security above all else and you have a Pixel, GrapheneOS should really be your only consideration.
LineageOS has a place for those who care less about security and more about features, "freedom", compatibility, community etc...
I was a LOS user and maintained my own forks for devices, but switching to GrapheneOS was a good decision and I don't really miss anything.
It might be important to mention, that Lineage OS is available on a number of the devices abandoned by their original vendors, so sometimes it may be a much better solution to get a Lineage OS onto their former "flagship" which stopped getting updates 18 months after the release.
So if the bootloader can be relocked and not passing Play Integrity scam is not a problem, Lineage may be a better option. Better than nothing, that is.