1) Queen Victoria's second son, Prince Alfred, Duke of Edinburgh.
2) Queen Victoria's third son, Prince Arthur, Duke of Connaught and Strathearn
The first eventually puts Canada in personal union with Saxe-Coburg and Gotha. This is mildly amusing.
The second, neglecting butterflies, takes a mildly convoluted route before Canadian personal union with Sweden. This is highly amusing, and more likely - I suspect that Prince Alfred would be passed over on the grounds of the inevitable personal union with Saxe-Coburg and Gotha.
Given that precedent, I suspect that Australia would also be made a principality. The next most senior male royal not in direct line of succession available in 1901 is the six year old Albert Frederick Arthur George, the future King George VI. Rather young, so we'll look elsewhere.
The Duke of Fife looks good, slightly awkward in a few years when he is succeeded by his daughter Princess Alexandra, married to the heir apparent of Prince Arthur of Canada - also named Arthur. Personal union of Canada and Australia is precisely what we were trying to avoid. Fortunately, or otherwise, both "Arthur of Australia" and his issue, Alastair - by then heir apparent to both Australia and Canada - predecease Princess Alexanda. She is then succeeded by her nephew, Prince James of Australia, who rules until 2015. At that date, given Australian dislike of the institution of hereditary monarchy, Australia becomes a Republic.
In Canada, Prince Arthur is succeeded in 1942 by Prince Alastair, then still heir apparent to Australia, who drinks his way out of a window in 1943. Next in line is Prince Gustaf, also incidentally Crown Prince of Sweden. This is massively controversial, given his suspected pro-German leanings - we assume here that Princess Margaret's marriage goes as OTL and none of this dynastic manoeuvring averts the rise of Hitler. Big assumptions, I know.
He is of course kept on a short leash, and on no account is his distant relative the former King Edward VIII despatched to Canada lest the two monarchs plot between them. The Duke of Windsor probably gets sent to Hawaii or Tristan da Cunha instead of Bermuda. Upon the death of Prince Gustaf in 1947 - the second Prince of Canada to die in unusual circumstances - he is succeeded by his infant son, Carl, who succeeded to the throne of Sweden in 1973.
Today, Prince Carl of Canada remains on the throne. As King of Sweden, Prince Carl's responsibilities are primarily ceremonial, whilst the Prince of Canada retains a role in the governance of the realm. Accordingly, he spends much of his time in Canada, though frequently visiting Sweden. Canada not having passed the same primogeniture reforms as Sweden, his heir remains the Crown Prince Carl.
The principalities of New Zealand, Newfoundland, South Africa
et al are left as an exercise for the reader.