Bilbo and Sam. (I suppose Frodo tried to give it up, but ended up stuck with it. He also suffered permanent damage from the Witch King's blade.) Bilbo obviously carried it for years compared to Sam's days.

As I recall, the book emphasizes that Bilbo and Frodo go to the West to give them rest from the burdens they've carried. Sam, in contrast, has not tired of life on Middle earth.

Which is another way to think about the effect of the ring--Not so much worthiness and how well did you pass a test as simply how much did carrying it damage you. Did it damage Sam less because he gave it up freely, or could he give it up freely because it had damaged him less?

Either way, it says something about the scars we carry both because of the things we've suffered and the choices we've made. Those scars are real, even if we still get to sail into the West despite (because of?) them.