I guess it all depends on who, where and when. For me, in no particular order:

A private recording of Roy Williamson singing "Flower of Scotland" - sad, pensive and completely different from the rugby/football match version we so often hear.

Hamish Henderson, already in his 80s, singing "Freedom Come-All-Ye" alone and unaccompanied standing on a huge stage at a predominantly rock concert with an audience of some 200,000 mostly young people, when you could have heard a hair, never mind a pin, drop. I wasn't the only one in tears!

Sheena Wellington singing "A Man's A Man For A' That" at the opening of the Scottish Parliament when everyone, completely unrehearsed, joined in the last verse:
Then let us pray that come it may
For come it will for a' that
That strength and worth o'er a' the earth
Shall bear the gree for a' that
For a' that and a' that
It's coming yet for a' that
That man tae man the world o'er
Shall brothers be for a' that.

And yes, "Auld Lang Syne" particularly when played by massed Pipes and Drums.

Famous? Perhaps for no-one except me but ceertainly what Scotland is all about.

Eddie