I was born and lived in Central Ontario and worked in the GTA most of my life. I have a business degree from a school in Ontario and moved out to Edmonton about 18 months ago for a progressive opportunity outside of the energy sector.
The most opportunities are in the energy sector, but there are more opportunities here in general. The first time I went back to Ontario I went for 24 hours for a charity golf tournament I'm involved in. I drove from Pearson, up to Newmarket (birthplace or Connor McDavid to keep the hockey angle going) for breakfast with Mom, over to the tournament at Lionhead in Brampton, out to Scarborough to pick up Leaf tickets for the auction, Back to Lionhead, and then back to Pearson. I saw more "help wanted" signs at Edmonton International Airport then I did in all that driving around (and through) Ontario's biggest city.
As others have pointed out though, that doesn't necessarily mean jobs that would utilize the skills that you've learned in school. I'm assuming "International Business" covers a lot general business courses (statistics, economics, communications, leadership etc.) so there should be opportunities in both Calgary and Edmonton. It depends on what you are looking to do...do you want to work in banking, energy, government, insurance, technology?
I looked at opportunities in both Calgary and Edmonton, and I prefer Edmonton. Calgary has the mountains, we have the river valley. I think that the number of universities makes things a little more multi-cultural and contributes to a neat arts scene. The Whyte Avenue area kind of reminds of me Queen street. Neither city is anywhere near being as big as Toronto but I like it here. It's considerably more affordable than Toronto, and hardly has any traffic (Calgary does have bad traffic - not as bad as Toronto, but bad enough). After 78km / 1 hr 45 minute commute for the past 20 years, the 15km / 20 min commute was a big feature here. Cost of living (especially housing, property taxes, sales taxes, and income taxes in the higher brackets) are a LOT lower than Toronto. Housing will be more than Niagara region. It's colder but it's sunnier and snows less (a LOT less than Barrie or anywhere else in the Ontario snow belt). It feels a little American in some ways (political climate and franchises)...not necessarily better or worse but different...also you'll have to get used to not buying bags of milk...
The biggest thing I miss (other than family and friends) is baseball...
Like others have said I would recommend visiting both cities and deciding which you like best and trying to line up interviews for opportunities that might interest you.
Hope that information is somewhat helpful, feel free to DM me with specific questions. I may also be able to help you further depending on your qualifications and the field that you want to get into.