I think there was a citylab article posted a few weeks ago, where they determined the most profitable rental incomes are in low income areas, I believe somewhere in Wisconsin they mentioned.

The article differentiated two different investment strategies:

Low income property with a decent profit over monthly expenses.

High income property with little to no monthly profit, but large appreciation in value over a short time period.

So, instead of buuying one or two high income properties, one could purchase 5 to 10 low income units.

I found it interesting and a new perspective for me.