I know this post is a little old, but I hear landlords talking about this topic all the time. I used appfolio for a while with a property management company I used to work for. While there was a decent cost to it, I found it extremely helpful in so many ways, particularly for lease creation, marketing leads for rentals, communication with tenants (through their texting service), and maintenance requests/tracking.
But if anyone is looking for free software, Cozy works well for small-scale landlording. It allows you to receive payments, market rentals, and take maintenance tickets. There’s not much depth to the free functions, but if you don’t have many properties or are just getting started, I would highly recommend Cozy.