I just saw your post a little while ago, so here are some of my choices:
Season 1 - The pilot episode where Eleanor Parker attends her own funeral.
Season 2 - Whodunit with Celeste Holm
Nightmare with Pamela Franklin and Ray Milland
Pentagram with Florence Henderson
Season 3 - Hit Man with David Doyle
Goose for the Gander with Doris Roberts and Abe Vigoda
Class of 69 with Adrienne Barbeau
Dr. Jekyll & Miss Hyde with rosemary Forsyth and Don Stroud
Season 4 - The Devil & Mandy Breem with Roddy McDowall and Carol Lynley
Concerto of Death with Dennis Cole
Jack the Ripper (Victor Buono was GREAT in that role!)
Crescendo / 3 Feathers with Toni Tenille and Hugh O'Brian
The Chateau with David Hedison
Season 5 - Devil & Mr. Roarke / Ziegfeld Girls
Funny Man with Jimmy Dean
Quiz Masters with Jan Murray and Gene Rayburn
Season 6 - Curse of the Moreaus with Stuart Whitman
Face of Fire with Lynn Redgrave
Season 7 - Curtain Call with Milton Berle
Roarke's Sacrifice with Cyd Charisse
As a general rule, I disliked any segment that was about Roarke or Tattoo. (E.g., Roarke's romance with Samantha Eggar, Tattoo becoming a love god, etc.).
I also dislike any episode that has to do with people time-traveling to take part in either of the World Wars.
Mine is probably "Vampire" with Robert Reed; very corny, but 70's vampires rule.