...in my opinion, anyway. Glad to hear yours in the comments (click on the category, "Great Moments in Obscure Rock 'n' Roll" to see this year's selections). Here's mine (with apologies to The Nazz, Bloodrock, Poobah, and The Frost, who almost made it):
Hawkwind, "Mirror of Illusion," 1970
Fat Mattress, "Black Sheep of the Family," 1969
Freedom's Children, "That Did It," 1971