The 1937 series exists because of thirteen months that rearranged everything: legislation requiring bilingual notes, the death of George V in January 1936, and the abdication of Edward VIII before year's end. The Bank answered all three at once - a single note for both languages, English on the left of the portrait and French on the right, with the new King George VI moved to the centre of the note to make the arrangement work. The dual English-and-French printings of 1935 were dead within two years of birth.
The Osborne dollar is the affordable front row seat to that change: fifty million printed, so an honest mid-grade example costs little, and it carries the first signature pair of the first bilingual series. It also introduced the modern serial number - unique per note, with the two-letter fraction prefix - retiring the sheet-and-check-letter system of 1935.
The best value in the series is history per dollar, and the Osborne $1 wins it: the earliest form of the note every later Canadian note descends from, at common-note money.
Mintage figures: United States Mint (Annual Report of the Director of the Mint), Royal Canadian Mint records, and — for the 1935 banknote issue — Bank of Canada printage records as published in the Charlton Standard Catalogue of Canadian Government Paper Money, cross-checked across independent published references. Specifications: United States Mint coin specifications.