http://jacksonupperco.com/2014/01/28/the-ten-best-gilligans-island-episodes-of-season-one/

Mine are:
(in no particular preference)

Good Night, Sweet Skipper
Sound of Quacking
Waiting for Watubi
Water, Water Everywhere
Little Island, Big Gun
St. Gilligan and The Dragon
New Neighbor Sam
Physical Fatness
My Fair Gilligan
A Nose By Any Other Name