Gilligan, no question--for all the reasons you give. Plus all the time Bob Denver spent as beatnik Maynard G. Krebs on Dobie Gillis.

Honorary Stowaway Award: Ida Lupino, who directed four episodes of the series: https://moviemovieblogblog.wordpress.com/2018/05/06/ida-lupino-directs-four-episodes-of-gilligans-island/