The ideal response is – maximize contributions to BOTH! But, for many people that’s not realistic.
There’s no simple way to determine if an RRSP or TFSA is best to start with. RRSPs are great to reduce your taxable income. But, if you’re in a lower tax bracket, TFSAs may be a better account to save in. If you need flexibility to fund financial goals aside from retirement, like a home renovation, it’s better to save in a TFSA. And, if you expect to earn a generous pension, the combined income from that and your RRSP withdrawals could drive you into a higher tax bracket in retirement than when you were working.