I’ve seen three of them so far: USA, Canada, and Australia. I know many other countries have a version of this but they’re very difficult to find.
The American version got me started and it’s natural because I started watching cooking shows because of Gordon Ramsay. The Canadian one came a few years later, and I still enjoy it but not as much as the other two.
The best, by far, is the Aussie version. The main reasons are that the standard of cooking is incredible; ingredients and cuisines are very broad; the hosts are just very likeable; and the contestants are the most likeable. I think it all comes down to how it’s aired/produced since the North American versions like to play up rivalries and such but in the Aussie version you don’t get any of that nonsense. I can never tell if there’s genuine friction between the Aussie contestants and they all seem so stoked when others do well - they focus on building each other up and then trying to best that rather than trying to bring others down.
The level of difficulty on some challenges is immense, too. I think if winners of Australia/USA/Canada were to face-off in some sort of Masterchef Colonial Challenge the Aussies would win, hands down.
Also, the Aussie version is 5 episodes a week for around 12-13 weeks. I think the last season was 60+ episodes and I loved all of it.
TL;DR: Australians seem to be pretty awesome.