I recently moved from the US to Canada, and Canada recognizes Roth IRAs, which is great. So we converted our traditional IRAs to Roth before we moved. In hindsight, it may have been better to focus on our taxable account rather than tax deferred (since taxes rates are higher here) but at the same time, since our income in retirement should be pretty low, our taxes here might still be lower. One thing we've been careful about is avoiding foreign domiciled ETFs in our taxable account so that we don't need to do PFIC filing. So basically we hold Canadian ETFs in our tax-sheltered Canadian accounts, and then we'll hold individual stocks in our Canadian dollar taxable account. We're keeping our existing US dollar taxable account in US ETFs, with a Canadian brokerage. It has definitely been a learning curve, but it ultimately hasn't been that hard.
Another thing to consider is how friendly your brokerage is to expats. I've asked specifically about Canada, but based on my phone calls Interactive Brokers and Vanguard are NOT friendly to US Citizens living in Canada, while TD Ameritrade, Fidelity and TIAA are. This can certainly change, though.