What are the best places in Canada to get the most competitive currency exchange rates? How do currency exchange services in major cities compare? What are some popular options like Knightsbridge Foreign Exchange, Gastown Currency Exchange, and Calforex and how do they differ? What factors such as fees, exchange margins, and convenience should be considered when choosing a currency exchange provider? How do banks, ATMs, and exchange kiosks compare in terms of getting the best rates in Canada?