I had the Bernstein Nielsen 3rd and liked it a lot.  I also had Bernstein's
recording of the 5th and I also had Ormandy's reading of the 6th symphony.

I can listen to Nielsen for a while, and enjoy his "genius".  Of his
symphonies I like the 3rd the best, and the section of the 5th where
Nielsen instructs the snare drummer to improvise and try to throw the
rest of the orchestra off tempo is also a good listen. Of course, that
requires a snare drummer who can cut loose.

John Ogden recorded a LP of Nielsen's piano music.  I had the album but
couldn't get connected to the music.

NIelsen's concerti for various instruments leave me cold.

Dave Harman