According to a study from VisionMobile, Android is the least open among the eight open source mobile platforms.
Android, Eclipse, the Linux kernel, MeeGo, Firefox, Qt, Symbian (based on the governance model of the Symbian Foundation prior to the the platform's transition back to a closed model), and WebKit were analyzed.
While openness may seem all well and good for a platform's success, fans of the walled garden platform iOS may argue the other side. After all isn't investment an even more important factor in developing a quality and successful product?
I have and like Android, iOS, Linux and Symbian devices, but I can't tell any real user advantage to one being more open.