How do I pick a good property management company?

I'm looking at getting a property management company to manage my 5 properties in the Denver Metro market so I can focus more on growing the business as stated on multiple bigger pockets podcasts. Any recommendations of how to pick a good company and what questions I should ask? I gotta admit, I'm a little nervous about handing over 6-10% of my profits to a company that isn't working in my best interest. Thanks ahead of time for the help!!