It's the donor who gets the tax credit.   Eg:  If I donate $100 to the Liberals, $75 is returned to me in the form of a credit.    If you donate the same to the CPC, you get the same credit.

The sum total for the credits was always far larger than the per-vote subsidy.    Far larger (about 60% more costly to tax payers).     Furthermore, studies have shown that political donations are skewed (obviously to people who have enough disposable income to donate).    The per-vote subsidy was less costly (to tax payers) and more "democratic" as it reflected voters in terms of maintaining political parties via tax dollars.