Based on what you said, would purchasing ETFs in my TFSA (tracking international indexes) be a good option for my rainy day fund? I'm in the same boat where I don't plan on staying in SA in the long-term but I need a place for my rainy day fund. A lot of people have recommended TymeBank but this is only available for SA citizens and PR holders, which I'm neither. Interest rates in the bigger banks suck at the moment.
Unfortunately TFSA will not work for you, you will be best served by the highest interest easy access account available to you. Equities and Retirement vehicles are all long term investments, that are not suitable for short term 3-6 month rainy day funds.
