[Elrian]

Sounds like his definition of greatness was meant in an all around way. Galadriel was great in her own way, yeah she made a phial, took over the rule of the Galadhrim and some other great or not so extremely great deeds. Feanor created some Silmarils, that a Valar coveted. When his father was killed and his gems stolen he went absolutely ballistic and goes on a quest to recover his own, whereby he kills his own kind to gain ships, then deserts his own followers by taking the ships then burning them so the rest of the Noldor cannot follow the quest that they swore some oath for. Luthien who is just some half Telerin Elf or Sindar, half Maia, never been to Valinor, hasn't seen the light of the two Trees, goes on a quest for love to gain the Silmaril from Morgoth, sings him simple so they can recover the stone. Then when her guy dies she follows him and sings yet another Valar into submission and gains life albiet a mortal one for herself and her guy. So why was this Luthien so great, hmmm with the power in her song she could do what those other two could never do,heck she could get what ever she wanted from the Valar all she had to do was sing! She did what she did for love, not power, or material gain, or revenge. She was also prettier and more well loved by her people, she didn't desire power like the other two. Also by Tolkien himself saying that she was the greatest of the Eldar should be proof enough.