If you need to ask, probably graphene. IMHO the only downside to graphene is that they consider the user to be an attack vector and therefore eg. actively object to allowing root access, while lineage is less bothered by it. If you don't care about that, use graphene. If you do, probably go with lineage.
Didn't lineage remove built in root years ago? That means you still need a third party root solution like magisk. Factoring that in there's not much practical difference between lineage and graphene.
the only downside to graphene is that they consider the user to be an attack vector
In other words, just like Google.