Favorite software for a Landlord?

[Jeff Schroeder]

I'm relatively new to REI, but have had a single rental property for ~3 years that does well. My father on the other hand, has ~20+ properties and tracks everything manually in a spreadsheet. While I could likely write some decent landlord software, I'd rather see if someone else has done a better job than me.

What, if any, software do you use to manage things? I've seen Appfolio, but it seems like buying a Porsche when a Volvo will do as it is a bit overpriced.