I really like Yardi. I have also used Rent Pro which was also not bad. Yardi is quite expensive but it does the job. You can do rent roll, keep track of rents and concessions, call max is also a nice feature too (not sure if it came with yardi but we used it). Yardi also does all the maintenance issues and even keeps track of who performed work and how much it cost to complete the job.
I have used Yardi, OneSite, and Buildium. I love OneSite. Everything is very user friendly, the reports are easy to access, and everything just runs very smooth.