The obvious & knee-jerk response would be
Mystery To Me,
but, I think both
Penguin &
Heroes Are Hard To Find have both seemed to grow in stature as the years move along. I'd almost give it a 3-way tie among those three.
He had a great start with the title cut of
Future Games and "Lay It All Down" has seem to get better over time, as well (including the alternate version on
The Chain box. "Sentimental Lady" was great, but I didn't think "The Ghost" lived up to the expectations laid down after
Future Games (plus, I think
Bare Trees was really Danny Kirwan's album to shine...too bad he lost it on that subsequent tour).