Had to think about this one alot and am still undecided.
I thought it would be an easy decision with Luke, but then I thought that Frodo had to carry a heavy, corrupting, and independent evil around his neck during his quest. He had no training, experience, or anything of the sort, not to mention a size disadvantage. He could have been killed a ton of times without his companions, but then so would have Luke. Luke's quest seemed to have been chosen for him and victory was an option, but Frodo's was more like a martyrs. He knew the quest would kill him and success was never more than a fool's hope. Hard to keep going, when you know death is at the end.
After the end, Luke had the glamour of being a hero and jedi knight. On the other hand, Frodo returned to normal life with hardly any acclaim...He stayed a hobbit throughout.
I still might choose Luke due to what he became, but won't look past the extreme adversity facing Frodo.