My favorite is Summertime, with Being Drunk's A Lot Like Loving You a close second.
From Kenny Chesney, my favorite all time song that he does is,"I Would Have Done A lot of Things Different"! This one really hits the 'heart' ! And my second favorite is "You Had Me At Hello"!
both are good songs . . . it is so hard to choose because each one makes me think of different things and I think my favorite changes with my moods too! :-)