14. Ain’t No Mountain High Enough — Marvin Gaye and Tammi Terrell (1967)
If this song doesn’t get you emotionally invested, none will. The chemistry between these two vocalists is undeniable. Terrell’s rich notes bounce in perfect cohesion with Gaye’s velvety presentation. You’d just as assume the duo to be a married couple (though they were just close friends). This is a song which will stand the test of time, and will be prevalent in any era.