@Andriy Likhman Midwest - Indy, Kansas City Columus Ohio, etc. The South - Alabama, Mississippi, letc. Are good starting points. Suggest you go on zillow, type in a city, enter your criteria and read anout several properties - this is just to get a feel/gauge for what work for you. Next do BP forum searches of your short list of cities/states - so many posts to read through with great intel. I'm biases towards Ohio because there are several very active posters in those markets.
On a side note, picking the right team is as important, if not more important, than picking the city - within reason. There's many good investment cities, so honestly I wouldn't sweat picking "the best". Make sure to interview several realtors and make sure that they really are "investor friendly". Any realtor can claim they are investor friendly, but if they can't refer you to several good lenders, property managers and contractors they are just another sales person - dime a dozen.