I actually agree that, based on my experiences, osteopathic residencies don't attract as good a quality of residents. In the rotations I did at a hospital that only had osteopathic residencies, I felt like I knew more than the residents. One of the attendings even told the resident, "Don't let your medical student (me) show you up." One resident I worked with didn't even know that the Bethesda system for Pap smears had that name
This is only my experience in one hospital, so I know I can't generalize, but it seems like many DO students on SDN have had similar experiences.
If you are going to apply to osteopathic residencies, apply to the ones that are dually accredited. These residencies are usually of higher quality, because they meet both the AOA and the ACGME's standards.