Depends as much on what passport you hold as which airline(s) you intend to fly. With the downgrading of FF programs overall, circumstances may dictate a program that routes you through various transit airports in countries that may have visa restrictions. As well, the fare paid will determine what you can expect to earn in the way of miles you can redeem for flights in the future, or if you can even attain a tier of elite status in the course of a single year to receive benefits on future flights.

KLM/Air France may afford a better option than either Aeroplan's partners (AC, Egyptair, LH) or Avios' (BA, AA, IB). Those are the airlines that would have the most flights into northern Africa. 20K flight miles might only translate into 10K redeemable or elite status miles on discount fares depending upon the airline and the FF program you join. Also, would your time and financial resources permit traveling around Canada during your time here, and can you get a visa to visit the USA so you might have some flights down there?

What airline(s) have you flown in the past? To get to Toronto? If you provide more details, I am sure you can get some reliable advice that suits your needs and gives you a 2-3 years strategy to maximize your investment while studying over here.