The Greatest Elf of Middle-earth?

[Orald]

These first three quotes are from UT.

In this he emphasized the commanding stature of Galadriel already in Valinor, the equal if unlike endowments of Fëanor

Galadriel was the greatest of the Noldor, except Fëanor maybe, though she was wiser than he, and her wisdom increased with the long years.

For Fëanor beheld the hair of Galadriel with wonder and delight. He begged three times for a tress, but Galadriel would not give him even one hair. These two kinsfolk, the greatest of the Eldar of Valinor, were unfriends for ever.

Feanor's death, from the Silmarillion:

Thus ended the mightiest of the Noldor, of whose deeds came both their greatest renown and their most grievous woe.

I think Tolkien's careful use of Noldor and Eldar of Valinor does more than just help the theory that Luthien was the greatest of elves. Luthien, Galadriel, and Feanor might be the leaders of the pack, but I think there would be a close race after them. We have Celebrimbor, Finrod, Beleg, Cirdan and several others that all make a good show.