I do believe NYC will bounce back, due to the diversity of all the businesses here.

Lubbock is also a solid rental market and has a fairly diverse economy. 

Industry diversity is also important to consider in my opinion, as population growth and supply of housing can all be affected if a city is reliant just a few industries to provide jobs.

From a macro level the region is strong and diverse economically, while still being fairly affordable for the rents a good unit will demand. 

The most important things to look for in any market are growing populations, growing jobs, modern economies with a diverse employment base, business friendly climate, low property taxes and favorable landlord tenant laws. 

Look for Metropolitan Statistical Areas (MSA's) that have growing populations, growing jobs, modern/diverse economies where businesses are investing capital.

A neighborhood can include more than one zip and a zip can be incredibly diverse here in Philly. 

Louis is a large and diverse market.

However, if you're specifically set on one of those markets I'd recommend Kansas City - landlord friendly state, lower property taxes, increasing population and diverse economy, a good supply of potential rentals that product good cash flow with a decent chance of future appreciation.

Some people STR a literal 100 sq ft Native American teepee...doubt you'll find many takers for LTR on that thing.That said, portfolio diversity is important for lots of reasons.