@Simon Schermerhorn
To select a great market I would do the following:
I would start by defining my investing goals. That is, what is my appetite for cash flow vs appreciation. Also, how risk averse/affine am I. These parameters will help decide what kind of yields you are searching for, which you can use to filter down your list of macro markets.
Then I would start by looking at the macro market's fundamentals, that is the population, job and income growth over time.
After that, I would look to see what the rents and home prices are and how those are trending as well.
I would do a similar analysis, but at the sub-market level for the metro area you are considering investing in.
Other metrics that I find valuable to understand are household income, poverty, unemployment, and educational attainment. Also, the trend for the aforementioned metrics is also very important.
Other sources of data include:
Census Permit Survery
FBI uniform crime report
Bureau of Labor Statistics
U.S. Bureau of Economic Analysis
Climate data for weather risks analysis
Hope this helps!