The best landlord online tool

[Jane A.]

I need an online tool which will support paperless leases signing (as DocuSign), paperless application and background check. In addition it could have mobile application with maintenance requests and my contractors I could forward requests to. Payments support may be handy as well, but it is not a problem as I have already a system for that. Could you please share you experience and give me an advice what will work better in my situation of managing about 20 rental units ? I am not going to grow this portfolio or add any other models of RE business.