This is an interesting conversation. So far, seems Aussie's and Yank's favour pretty much the same cartridges.
In the States, the top 5 selling rifle cartridges are in ranking order:
1. 223 Remington
2. .308 Winchester
3. .30-06 Springfield.
4. 30-30 Winchester
5. .270 Winchester
II would be curious to see what the top 5 are in Europe.