Here's a hint: GrapheneOS has paid developers working on it full-time, while LineageOS is done by people in their spare time. Also, GrapheneOS has a collaboration with Motorola and through that gets for instance early access to security patches, and probably other things as well. And lastly, LineageOS supports roughly 10x the number of devices. It's significantly easier if you restrict yourself to Pixels.
Just for clarification (your points are very valid): the GrapheneOS developers have stated on several occasions that they getting embargoed patches from another OEM than Motorola.
GrapheneOS does not have circle battery.
> LineageOS really should be based directly on GrapheneOS.
What would that achieve?
LOS => most security, most usability, breadth of support