Well, It's great just to be able chat about Gordon and his songs. For me, there are too many, plus I feel there are three distinct era's for him (Before 76, 76-85 and post 85).
For me:
Pre 76: Circle Of Steel
76-85: I'm Not Supposed To Care
Post 85: I'll Prove My Love
Like I said, there's really not any song he's done that I dislike and too many to single out one (unless forced to do so---"I'm Not Supposed To Care").