No.1 Most Popular Coin Or Type Collected In These Regions?

I think the most common answer would be the staple coins of any country of the collector in other words, the common definitive types. In the U.S. it would be Wheat Cents, for example.

Australian collectors love collecting two bobs - Florins to our American friends.

I once, many years ago, made up a type set of Australian gold , silver and bronze coins, with each type represented by the rarest date, with the exception of the 1930 Penny, and the 1855 Half Sovereign. They were represented by an 1856 Half Sovereign and a 1925 Penny. The Adelaide Pound I had was in good VF condition. The Melbourne Centenary Florin I had was what Americans would grade at MS65, with Foy's bag. That collection was sold.

I have built an Ancients and World collection since then.