Buildium is by far the best softwate out there no matter how many properties you are managing. I have used Rentmaster which is limiting by the number of users that can see what is actually going on with the properties. I have used rentright which is absolutely the worst software I have ever used. If you have over 40 properties in the system it will lock up and casue major issues for your valuable information.
Buildium is great in the fact that it allows many users to have access to the software. You can control what people can and can't see when they access the system. The only drawback to buildium is that it doesn't manage your company books that well. You will have to have a seperate system to track your companies financials. For that consult your local CPA to set that up. My partner is a CPA so he set that up for our property management company. It is a GREAT COMMUNICATION tool for everyone that you talk to. The software is very scalable as well, so if you have a single family home or 1000 units the softeware still works. Alot of software stops working after you have so many units and when you have to switch software it will almost shut your company down for a short period of time or may never recover depending on how many units you have.