I choose classical music by my mood and the composer. The earlier the composer wrote the more peaceful the music. Haydn was born 1732, nice quiet music. All the Bach family were organist and rather somber. They used chords never heard of before. They inspired the Beatles. Russian composers like Wagner, Rachmaninoff, and Rimsky-Korsakov were in the 1800’s, and very emotional. Wagner, with the volume turned up makes for real excitement. Chopin and Liszt are quieter, more thoughtful. Mozart is a man set apart. I’ve read that babies raised with Mozart played in the background are more intelligent than other children.
These opinions are from a person who has never studied music, just loves it.