As an US Citizen, you may hear and read horror stories about the TFSA. However, there is no IRS ruling (yet) as to whether the TFSA is a trust (and therefore requiring complex paperwork). Check out Max Reed's books and articles as he and the folks at SKL seem to have the best understanding of the IRS rules. I still suggest prioritizing RRSP over TFSA because it is simpler and you get the tax deductions now. Statistically, this will ultimately lead to higher returns. Note: RESPs are definitely trusts in the eye of the IRS and require complicated paperwork. There is not yet any ruling on the TFSA.
Unlike the TFSA, the Roth IRA problem is not a grey area and you could really have a problem with CRA. The Canadian government does not recognize this type of account - it only recognizes 401(k)/403(b)/equiv and traditional IRAs. Technically, the minute you make a "Canadian contribution" to a Roth IRA, the entire account appears as a taxable/unregistered account in the eyes of the CRA. I suggest reading about Canadian contributions and the status. For newcomers to Canada who already have Roth IRAs in the States before immigrating to Canada, such people must declare in the first year the existence (and location, value, account numbers...) of this account to a special office at the CRA. This declaration keeps the Roth IRA tax free in the eyes of the CRA. But once you are in Canada you should never ever contribute to it again, otherwise the CRA deems the entire thing as taxable.