There are a lot of different systems out there and I spent a lot of money to play around with them. Examples Freedomsoft, Realeflow, ReiPro, Nesters, REI Blackbook and the list goes on. What I found is those systems are great for the specific parts of real estate they are designed for but they aren't scaleable nor can you customize it to fit your workflows and how you want your business to operate. Oh and I think I missed the biggest part, they are expensive.
Now don't get me wrong these are all fine systems and they can truely help you but they aren't the magic bullet that they claim it to be and you wont be sipping from the magic fountain of fortune if you spend the money on it.
I started to use a free system call Podio (Now they do have a paid version as well with better workflows and reporting if you need it). But its a very customizable system that you can use for every part of your business and its portable so I can use it fully on my phone or iPad while I am out looking at properties.
The main thing here is this. Don't rely on or spend a lot of time on the system that you are using for your business because its not the system that makes the business its you that makes the business. Get out there and find and close deals. The system will form over time.