I invest in both markets and both have there pros and cons.
Birmingham has better inventory and you get more bang for your buck with lower purchase prices and really nice homes built post 1960's in some really beautiful areas such as center point. I was very impressed. The cons are they have a large section 8 tenant population and vacancy has been an issue for me as all 3 of my homes took over 4 months to rent. When you compare statistics like miles post above Birmingham is clearly not that great.
Indianapolis is definitely booming right now. Especially the inner city. The economy and things like job growth and population growth are also very good. Strong millennial population for renting in the inner city areas in and around fountain square and Bates Hendricks. This is where I invest, however I will say it takes the right company to pull it off in these areas and that for me is FS Houses. The cons are low inventory and crazy competition as everyone wants to invest in Indy right now. Prices have gone up recently and I question if this will continue. The homes are older and can come with more repairs.
Best advice I can give everyone make sure you find a good company to work with as this is just as important as finding a market. Good luck