Because the above method doesn't work, I have done correlations between different artists I like and the music recommended for that artist. (Example Arists A: Similar B C D; Artists E: Similar C D, then it would recommend C=4 point, D=4 points, B=2 point)
This method sort of works, but it mainly yields music I find 'acceptable' not music I find good.
Music should IMO be recommended using genre/tags(artists, year, ...) as well as:
(rather long list:) tempo, complexity of the music, instruments, amount of instruments, how monotone or varied to music is, then there is music that uses notes to keep you in short suspense and others in long suspense, general sound of the music (rock would be 'rough' while violin would generally be 'smooth'), music patterns, music pattern genre, ...
And then you need to train a small neural net per person to figure out witch of all these features is important to the person you are recommending music to.
(Edit: added to list of features to look for in music)