Depends on the location and the asset quality. In Edmonton or most major cities 25% down or more is quite common. In small towns 15% with CMHC is still doable in some instances.
Eliminate your feelings. Go with cold hard numbers.
The main benefit of CMHC is lower rates, by about 1%, as it insures the bank's risk of lending money to you. For this you pay a premium, usually added to the mortgage. Thus, the break even point is about 3-4.5 years out, depending on the LTV and fee % you pay. The second benefit is that this "CMHC ticket" is good for the amortization period, usually 25 years, so if you renew in 5 years with perhaps a different bank, you will probably get a much lower rate again, and again, every 5 years.