There are many great Elven warriors that are named, but here are a few that are quite explicitly considered as "the most powerful".
Explicitly mentioned as powerful
Fëanor
- Went into combat with several Balrogs, perished in the attempt
For Fëanor was made the mightiest in all parts of the body and the mind, in valour, in endurance, in beauty, in understanding, in skill, in strength and in subtlety alike, of all the Children of Ilúvatar, and a bright flame was in him.
As mentioned in the quote, Fëanor was mightier; in body, mind, valour, endurance, beauty, understanding, skill, strength and subtetly, than all the Children of Ilúvatar.
Fingolfin
- Went into combat with Morgoth himself, perished in the attempt: not before inflicting mortal wounds
Fingolfin was said to be the strongest, most steadfast, and most valiant of Finwë's sons.
Of course, there's also Ecthelion, who killed Gothmog Lord of Balrogs, and Elu Thingol, who's noted as "the mightiest Eldar save second to Feanor only". Based on how you want to interpret the sources, you could say that Fingolfin was the most powerful Elven warrior, give that he was able to wound Morgoth 7 times.
Galadriel
While not a warrior, she was explicitly considered to be a mighty.
A queen she [Galadriel] was of the woodland Elves, the wife of Celeborn of Doriath, yet she herself was of the Noldor and remembered the Day before days in Valinor, and she was the mightiest and fairest of all the Elves that remained in Middle-earth.
Not explicitly mentioned as powerful
Ecthelion
- Went into combat with Gothmog Lord of Balrogs, perished in the attempt: not before succeeding in killing Gothmog
Fingon
- Went into combat with several Balrogs, perished in the attempt
Glorfindel (pre-reembodiment)
- Went into combat with a Balrog, perished in the attempt: not before succeeding in killing the Balrog
Gil-galad
- Went into combat with Sauron (together with Elendil), perished in the attempt: not before succeeding in wounding Sauron
What about elves in the Dagor Dagorath?
I'll venture out to include the prophecy, which is told in full here:
Thus spake Mandos in prophecy, when the Gods sat in judgement in Valinor, and the rumour of his words was whispered among all the Elves of the West. When the world is old and the Powers grow weary, then Morgoth, seeing that the guard sleepeth, shall come back through the Door of Night out of the Timeless Void; and he shall destroy the Sun and Moon. But Eärendel shall descend upon him as a white and searing flame and drive him from the airs. Then shall the Last Battle be gathered on the fields of Valinor.
Thereafter shall Earth be broken and re-made, and the Silmarils shall be recovered out of Air and Earth and Sea; for Eärendel shall descend and surrender that flame which he hath had in keeping. Then Fëanor shall take the Three Jewels and bear them to Yavanna Palúrien; and he will break them and with their fire Yavanna will rekindle the Two Trees, and a great light shall come forth. And the Mountains of Valinor shall be levelled, so that the Light shall go out over all the world.
Eärendil (spelt Eärendel then) is the only Elf (formally Half-Elven) mentioned that goes to battle with Morgoth. Fëanor, reembodied, is mentioned as well, but his only mentioned role in the Dagorath is to "surrender" the Silmarils.