Stefan Bischof is part of the Project since its transition to the Eclipse Foundation. He made heaps of contributions in the form of TCKs and improvements since.
A list of his contributions:
https://github.com/osgi/osgi/pulls?q=is%3Apr+author%3Astbischof+
Beyond has he shown also engagement in other OSGi related projects like bndtools, OSGiTest and others. He is a strong advocate for the technology and encouraged others to join our calls.
Thus I'd like to nominate Stefan Bischof as Project Lead together with Timothy Ward.