Ours also takes 10% of gross rents received.
While you should feel some responsibility to your tenants, make sure that you pick a company that will take care of you. I was all fine and dandy managing our own place until some of my tenants decided to stop paying rent for various reasons. It escalated very quickly to the point where I felt in over my head. The management company simply accepted my keys and took care it. The owner of the management company knew what she was doing, and that was clear when we met to talk about doing business together. So, first and foremost, make sure you get a company/person who knows how to handle bad tenants.
The next thing to examine is their network of service operators. My management company has their own landscaping, maintenance, and repair people. They keep the property in good shape, and if something goes wrong it's repaired promptly and professionally. I receive a copy of all invoices and receipts for work done at the end of each month.
Finally, a good management company should be able to customize their response to your desires. If you want to give your tenants the ability to request quality of life repairs or upgrades, your management company should also be able to send one of their people over and do what is requested. When I first started with my management company, I would get frequent emails asking for permission to do this or that. Eventually I just told them to go ahead without my knowledge unless it was a serious big-ticket item. Now I just scan the monthly statements, and I get an email once a year or so about a water heater or furnace they have to replace.