In regards to the album that had, according to Dave Grohl, his favourite song he has ever written, when was it released?
These Days (Foo Fighters song): "These Days" is the third single, (fourth in the UK), from the American rock band Foo Fighters' seventh studio album "Wasting Light". These Days (Foo Fighters song):  Dave Grohl has stated that it is his favourite song that he has ever written. Wasting Light: Wasting Light is the seventh studio album by American rock band Foo Fighters. Wasting Light:  It was released on April 12, 2011 on RCA Records, and is the first album to feature rhythm guitarist Pat Smear since "The Colour and the Shape" (1997), making the band a five piece with the album.
April 12, 2011