Well, here it is nearly 4 years after my first post on this thread. Since then I've collected over half of Donovan's musical catalogue, mostly thanks to my Donovan-obsessed best friend Jon. New favorites would have to be:

Sailing Homeward
Curryland
Celtic Rock
Sing My Song
Epistle to Derrol
The Voyage of The Moon
Cosmic Wheels
To Sing For You
Celeste
There Is A Mountain
There Is An Ocean