Your doing well to start your research early. IT is vast
and Canada too.
In general, Canada is a resource based Economy and most
of its regional economies even in the 3-5 biggest cities ( there are no more than
that rely heavily on this), the major part of the economy is Resource extraction and real estate / construction and Agribusiness. This naturally means that a lot of its IT is related to this.
Here are the big cities in order of strength of their IT/Tech Sector
Toronto, Vancouver, Ottawa, Montreal, Calgary,
All cities come with big up and down sides depending on size culture infrastructure and
local economic dependencies, housing market, living cost as well as different climate challenges etc.
Now the question is more a lifestyle + life stage question, ie. are you on your own
do you have family and kids and what do you want for their upbringing.
There are a handful of up and coming "tech-centres" but I would not recommend them. They lack Career opportunities- despite their high growth in tech jobs, things are usually blown out of proportion, and the Talent looses out. It is a double sided sword to weigh between the generalized local hiring bias and scarcity to help you find a niche for you.