Do I have any say in whether I want to work for the new owner at all?

You always have a say in the sense that no one can force you, personally, to keep working somewhere against your will — you can resign at any point, sale or no sale. What you generally don't get is a veto over the sale itself or over the new owner as a business decision; that's a transaction between your employer and the buyer, and employees aren't parties to it or entitled to approve or block it.

Where your real leverage lies is in how the new terms of employment are set going forward. If the new owner wants to change meaningful terms of your job beyond what your existing employment already allows, you can decline those new terms, and depending on how significant the change is, that can trigger obligations on the employer's side, separate from your simple right to quit. Continuity of employment under the Employment Standards Act, 2000 means you don't lose your accumulated entitlements just by choosing not to continue on materially worse terms.

If you're unsure whether to stay, get very specific about exactly what is and isn't changing before deciding, rather than reacting to the idea of new ownership in the abstract.