"obviously it is in the end a matter of individual taste"
I rather suspect that's the beginning and end of it.
That "individual taste" will in turn be informed by whatever music the performer is used to listening to.

With most traditional songs and tunes, the melody is what is carried from one generation to another, as it can be sung and played on anything (even if it sometimes got written down too) and any harmony is entirely up to the performer.

It might be interesting to consider whether the chords are ever part of the song in folk music. In pop music they are, as is the entire arrangement including key instrumental solos, and in the tunes used as jazz "standards" the chord changes are almost more important than the melody as they are what the musicians improvise around. In classical music all the harmony is written out explicitly note by note, and in early baroque music a figured bass specified a bass line and implied chords but didn't say how they should be filled in. But what about contemporary folk songs? Some you could sing unaccompanied or with different-from-standard chords and they'd still be the same song - or would they?

Anahata