all the albums are great....each have their own character, and they all show how JM approaches songwriting during the different eras of his life.
But the best songwriting for me as the chord changes are more complex, in my opinion are all in the album "Room for Squares". Defining album nya yun
complex acoustic guitar parts( no such thing, body is a wonderland, why georgia)
Funk, and jazzy sounding chord changes (neon, city love)
bluesy soloing ( city love...especially live performances of this song--brilliant)
and then every song just containing melodies that make sense and then just brilliang lyrics.
Battle studies, Continuum, Heavier things are all just natural progressions of his maturity as a songwriting. I love them all, and he's just an awesome example to follow.
As far as Blues Guitarists that I'd like to emulate, he's up there with SRV, Hendrix, Clapton, BB king, Buddy Guy, Jonni Lang, Kenny Wayne Shepherd, Derek Trucks, Bramhall II... oh I almost forgot, Joe Bonamossa...