From career aspect, I am a front-end web developer, received Permanent Residence status for both New Zealand and Saskatchewan (Canada). Currently a citizen of India.
I cannot move out of Saskatchewan province, for next 3 years, as per the PR norms.
New Zealand has better climate. Canada is a better place for IT jobs.
But, in the long term, which one is the better place to live as a family man?
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Look at the Employment by major industry group, seasonally adjusted, by province. The main industries I know so far over there are agriculture and fishing. Since you are in IT, if you were to go in SK, the chances of getting a job in your field might be less.
Also the winters are brutal in SK. I have some friends over there but they are not in IT so they wouldn't know about the industry over there. (PS I am in Toronto). I have seen very early snowfall over there. And the weather is unpredictable (That stands for most of Canada by the way).
I don't know much about New Zealand, but I could find this about the employment diversities over there. Engineering is the fourth ranked industry over there. Also Auckland has some promising companies on their employment page.
For career, I would say SK is not the best option. I would recommend you to move to some other province like Ontario, Alberta, Quebec or British Columbia; but since you can't move outside for three years, that goes out of the picture.
For a family, the winters are going to be hard. You and your family will struggle adjusting to the weather here. Again this is from my personal experience.
Also there is not much difference between NZD and CAD if you're thinking about the finances too. So if you hopefully find a job in Auckland or any other major cities, you're off to having better chances over there than Canada.
I'll try to address some of your specific points:
New Zealand has better climate. Canada is a better place for IT jobs.
Canada is a really big place. While Canada as a whole you might consider "better" for IT jobs, if you are restricted to Saskatchewan then you will find your options greatly limited. On the other hand, Auckland has a thriving software development community, and you could move anywhere in New Zealand if you wanted to.
But my family would like to be in touch with indian society/festival. Unlike Canada, NZ has such problem.
Auckland is a multicultural city and has a wide range of cultural influences from India. As an example, the recent Auckland Diwali Festival attracted thousands of people:
"It's a demonstration of our diverse and accepting culture that it is also a festival that many other New Zealanders of all ethnic groups eagerly await," Mr Lotu-Iiga [Minister for Ethnic Communities] says.
If connection with Indian culture is important to you and your family, and it sounds like it is, I would strongly suggest considering your options in Auckland (largest city in the country, ~1.3 million people), versus your choice of much smaller city in Saskatchewan (max. ~200k people).
Google tells me that the Indian population within Auckland is roughly 146,500 people. The South Asian population within the entire province of Saskatchewan is only 5,130. (Keep in mind that when you're looking up things like this, the term "Indian" in Canada has historically been used to refer to the indigenous peoples, but the terms "aboriginal" or "First Nations" are preferred for those people today. People from the country of India are often referred to as "East Indian" or "South Asian".)
Coming from a country with essentially no snow and warm climate (India), the Saskatoon winters are going to be shocking. From about November through March, the average daily maximum temperature is below freezing (below 0° C). Snow can fall anytime from October through about May, sometimes quite a lot (see news story from April 2015). Driving will be difficult or impossible on some winter days.
