The problem is the ones that first come to mind are everyone else's favourites (The Christmas Sweater, Log-Driver's Waltz, The Cat Came Back). So my fave that isn't any of those is probably Blackfly, because growing up my dad would always sing that old song and it makes me think of him!
BTW on the topic of NFB shorts, Defector had a really good bit recently making the case that the NFB short Les Raquetteurs is basically the origin of modern sports filmmaking - even though it's a 1958 short about rural Québecois snowshoe racing.
