Quality of the Insurer. Check consumer reports - for example JD Power ratings - https://canada.jdpower.com/.
Make sure you're comparing plans with similar coverage. Each province imposes mandatory coverage requirements (which can differ slightly). Purchasing more comprehensive insurance is your choice.
Driving is risky and accidents happen. Drivers are responsible for their vehicle, passengers, other drivers, pedestrians/cyclists, and own lives.
If you drive, by law, you need auto-insurance - whether it's your own car or a rental. Mandatory coverage and coverage limits vary by province. It’s important to confirm your province's details.
Coverage consists of liability, collision, and accident benefits.
There is also comprehensive insurance that covers non-accident related damage to your car, like vandalism / theft.
Auto insurance does not cover any personal items you have in the car - your home insurance might.
If you were involved in a major accident, you need to call 911.
If it's a minor bump, stop your car once you're safely out of traffic.
What should you do after the accident?
Report the accident to the police.
Report it to your insurance company.
Be aware that some people stage accidents, then file claims for fake injuries / damage to their cars. You may become an unsuspecting target when driving a car and getting into a seemingly minor accident.