I had become extremely stressed & had fallen into depression.

But in general terms, Vancouver is a great place to live, but beware of the rain, it gets depressing at certain times of the year.

Do poor and depressed areas make good rental markets? 

If we enter depression.

The S&P 10% is lifetime return (since 1928) and includes the Great Depression and was used just as a reference. 

My grandparents were first generation Americans who were just starting their lives as young adults when the Depression hit - my grandfather spoke broken English and better Italian than English, and had a 5th grade education.

It's likely that they will have no equity in the home, especially if we are in the middle of a recession and their original 15 or 20% deposit has been eaten up by market depressions. 

One such tenant had a mental disability that lead to periodic depression, but once his mind cleared he was able to get back to work and pay his rent again.

For the rest of the country, you would need a prolonged depression before people picked up and left.

You'll have depressed cap rates in NJ due to taxes...but since you live here you already know that.