4. Joni Mitchell
Joni Mitchell has only released a single album in the past decade and played virtually no concerts, but it doesn't matter. The music she released in 1960s and 1970s will live forever. Everyone from Prince to David Crosby considers her one of the greatest songwriters to ever live, even if most people only know a handful of hits like "Big Yellow Taxi" and "Woodstock." Albums like Blue and Court and Spark only get better with age, and her recent bizarre interviews only serve to grow her legend.