Assuming 75% LTV  - Key indicators to look for: Population Growth, Low Vacancy, Landlord Friendliness, Rent vs Own Affordability, Annual income averages, Proximity to Economic Districts. - Value add or some sort of equity play. 

Economy, tenant demographics, landlord friendliness, new construction, etc.

Of course, things like this are better fixed with neighborly friendliness rather than lawyers, who get expensive and combative quickly (not the lawyers per-se, but the neighbors when they get legal letters).

It boils down to rent/price ratio, economic diversity, population size & growth, vacancy rates, landlord friendliness, and REI activity. 

I've met lots of investors from the Boston area who prefer NH for it's landlord-friendliness as well as better cash flow. 

@LaRussa Henderson there is no only 1 metric or criteria which is important.Needs to be a combination of few things, including: Landlord friendliness, job growth, population growth, price to rent ratio, demographics, median income, household income, house prices, crime rates etc etc. 

The first would be price vs rental income, in addition to that, I would look at location, the friendliness of the State/County/City on Tenant/Landlord issues, and who you have lined up in the location for "boots on the ground" (property manager, contractor, real estate agent, etc)

If you seriously consider Illinois as an out of state investor you need your head examined.Try landlord friendly states.Landlord-friendliness is definitely something to consider when choosing your market.... and didn't know Chicago was that bad?

My personal first filter, for example, is for landlord friendliness; I no longer invest in provinces where rent control is in place. 

I learned that honesty and friendliness is key to having a great tenant relationship.