Which is a better option among Master of Information Technology from Australia and Master of Computer Science from USA or Canada?

If you are looking for stay back Aus and Canada.

It depends on you and your ability of survival in which country you feel better and also is your family condition okay for these countries. And, also your Interest in the subject matters the most.

It is more about the university you want to go and it's ranking and the course you have to wish to pursue. Also, the financial aids are to be considered, so choose the country likewise.

You must go to Canada for further studies, because in Canada, you can easily get job and cover your expenses, while in USA, you can't do job .so, I would advise Canada rather than USA.

US higher Education is, undoubtedly, one of the best in this world. And CS in USA is really good. I think you should go for CS in USA. Best of luck.