Without a doubt Cock Of The North (even if it is a liqueur it's still a single malt)

My personal pick of the single malts would have to be St. Magdalene, although the distillery closed in the mid-80's. Out of my cabinet at present it'd be the 23yr old Glengoyne. Glenfarklas (sp?) if you can get it, otherwise, you cant go wrong with any Speyside.