Salams Fasyy,
I guess Leon's advice is most sound. Though i'm not sure if you can make the trip twice, financially that might be little hard specially when you are about to move to a new country. However, it makes perfect sense to first come alone, check out which city would work the best for your career and later bring family. Otherwise, it could become stressful for everyone.
Vancouver - living expenses are generally higher than other major cities in Canada (which are Toronto and Calgary
, but the weather is lot better than the rest of Canada. I'd love to move if i get a job a decent pay there.
Calgary - If you are in health care or IT and getting a job offer - definitely live in Calgary. Yes the weather is bit extreme, but still better than Edmonton (which is little north from Calgary). Life is lot more relaxed than Toronto. Gas is cheap and I guess the taxes are lower there too (not sure about the last one, perhaps someone can share their knowledge).
Toronto and its neighborhood called Greater Toronto Area (Mississauga, Oakville, Vaughan, Whitby, Ajax) has the most job opportunities, generally speaking, but also keep in mind that its very competitive. Most of the immigrants prefer to make Toronto their home and hence it has become saturated in many occupations. Yet, there are still opportunities. You'll have to come here and test the waters yourself. There is a huge muslim community in Mississauga. At the same time, you can get that throughout Toronto. But there is no doubt, that Toronto has the biggest muslim community as compared to other cities. Lots of masajids, schools and halal food outlets etc, available in Toronto and neighboring cities.
Alternatively, if you know some friends, relatives, its not a bad idea to live close to them. Being new in a country specially with family, you will need someone with family to become your support system, to help you with info new comers need in the beginning.