In reply to French Erick:
This is nigh on impossible with Andy since there's just so many!
Winter:
The Needle is one of the ones he was most proud of.
Got to have something at the Dubh Loch - Vertigo Wall?
Ditto for Beinn Eighe. Blood, Sweat and Frozen Tears? But again, there's so many.
Ditto for Lochnagar. Trail of Tears?
Summer:
Angel Face, Northumberland Wall, again something at the Dubh Loch - Vampire? Apparently this FFA was also his first E1 ever! Nowadays it seems to get E2. Maybe something on Creagan a' Coire Etchachan e.g. The Sharp End / King Crimson?
With Martin, The Godfather really stands out as the inaugural line up that great wall. Not sure how many VIIIs he did on Beinn Eighe. You could pick any really, they're probably all high quality. Boggle?
Blood, Sweat and Frozen Tears is a great choice since it was authored by the two of them.