What constitutes a great melody as opposed to a catchy tune or a hook?

I've always loved performers who can do great male-female melodies with vocals.

The greater melody that they're all part of.

From the 1930's through the 1960's there were hundreds of great new melodies written every year.

They're great melodies that still stand on their own, and are still sung, even after centuries have passed.

However, the film had great melodies by Ghantasala and Leela.

They keep it simple, with great melodies and pumping beats.

Though, if a song's got a great melody and corny lyrics I probably won't do it.

Each song has a great melody and a great sound.

"Planets (version II)", meanwhile, is a space rock song with a great melody.