Incorrect. Etchelion has a greater feat that Elrond, Glorfindel and Gil-Galad. It's not even close between them. Galadriel.. that's close. Feanor is obviously the best so I won't argue that one.
Well, like many of the Elven Kings an Queens she pretty much just sits on her ass most of the time. I guess she may have destroyed Dol Guldur on her own though that isn't my interpretation of the passage.
Ecthelion charged Gothmog and ran him into a fountain, dying in the process. To compare, Gimli could do this. Or Pippin.
Galadriel threw down the gates of Dol Guldur using her own powers. Ecthelion could not replicate this. He did not have a Ring of Power. He was not a near-First Born elf with thousands of years of experience under his belt.
If Ecthelion challenged Galadriel to a test of who could charge their helmets into a wall, he might win. If he challenged her with full measure of her power, he'd likely be squished like a gnat.