Should you delay claiming an RRSP deduction when a higher tax rate is expected in the future?

This is an Excel sheet that shows the math and answers the question :

When there is room in a TFSA it is always optimal to invest in that account while you delay an RRSP contribution until taxed at a higher rate.  But otherwise, which is optimal ... a) delay the contribution and invest in a normal taxed account, b) contribute to the RRSP now and take the deduction now, or c) contribute now but delay claiming the deduction?