I would suggest hire a professional in Appfolio to train you and hire someone else to do the data entry.My question to you is why did you switch to Appfolio?

The biggest thing I look for is population growth and the most up-to-date data that I have found is on the US Census Bureau website.

Like @Jon Crosby I use Mint (got to love free accounting), but then couple that with MinttoReport (small annual charge), a great tool so you can export your Mint data and report it once you setup tags and categories. 

AirDNA and Everbooked have pretty good occupancy data (you're limited in what you can get for free though).

Ok, so just did some research and initially, I was thinking RealtyTrac was the clear winner as they had TONS more info but BASED ON OTHER'S OPINIONS VIA GOOGLE SEARCH, it looks like they have a history of inaccurate data. 

Does anyone think that Chicago's record tax hikes and the possibility of a tax exemption for property's under $250K will lead to a new round of gentrification largely driven by Millenialls wanting to live in the City but not wanting the costs of staying in neighborhoods that are already gentrified?

I wasn't able to infer any new data from the public records.

Is there a way to access MLS data without being a real estate agent?  

In my county here in GA I can not access the mortgage data for the entire county.

Google Maps view, Rentometer.com - there are so many great sources to find out and take a data driven approach rather than a "gut feel" about the neighborhood.