I'm thinkin' Borgs probably like pop music - "YOU WILL BE ASSIMILATED...RESISTANCE IS FUTILE." Then again they seem to have no personalities. They probably have elevator music piped into their regeneration chambers.

Vulcans seem to like classical music. I also remember one original star trek episode where the Enterprise hosted a bunch of intersteller hippies and Spock played a harp thingie.

One episode or TNG -'The Inner Light- had an alien probe zapping Picard and causing him to live an entire lifetime in an extinct culture. There was a great deal of music, mostly involving a 'Ressikan flute,' which bore more than a passing resemblance to a Copeland pennywhistle.

More about the episode and some photos here

A midi of the beautiful (but too short, and it's sequenced in 'A' instead of nice whistle-friendly 'D' too, durn it!) tune is here