The choice is actually quite easy: LineageOS isn't really a valid choice if you're after security and privacy. It substantially rolls back security and somewhat reduces privacy compared to the Android Open Source Project.

LineageOS's goal is to provide features and OS updates to as many phones as possible. They do that at the expense of security and privacy.

So, if you care about security, privacy, you should use GrapheneOS. If you don't, you should use LineageOS.