You can read about the Ontario Health Insurance plan on their
website. Like the pp says there is a three month probationary period before benefits will take effect and that is assuming you meet their qualifications.
As well with the Quebec plan there is a 3 month wait before benefits are instated.
You can read more about their plan on this
site
Again, the availability of benefits is benefits depends on you meeting their qualifications.
If by chance you do not meet the qualifications to be covered under the provincial health plan, you can get health insurance through Blue Cross or other insurance companies. Most provinces also have deductables, so you may want to look into which province is more feesible. Canadians living within Canada, trying to get health insurance is normally easier than moving from other countries, so expect a hassle, and make sure you do everything they ask. I have seen people have delays with their healthcare insurance because not all their documents from other sectors of the government have not been completed as they should be, or quickly as they should be.
Both provinces have their pros and cons. McGill University offers IVM which is one of the top clinics in the world to perfect this infertility treatment, and yet Ontario, has funding for when someone over stimulates on an Injectable/iui cycle. This can be helpful because it pays for majority of an IVF cycle should you wish to convert from the iui cycle.
If you have the opportunity to come up and spend a few days here, prior to moving, it may give you a better idea to where you want to live. Just because someone likes an area, doesn't mean it's right for you and vice versa.
Good luck with the move.