It is difficult to pick a favorite episode. The series had great writing, stars, and original plot twists. Many episodes I call a favorite have been named.
Does anyone remember "Steel" with Lee Marvin? In a future where the too brutal sport of boxing is banned the fighting is done by mechanical men. A down on his luck ex-fighter/manager (Marvin) out of necessity steps into the boxing ring against a superior fighting machine.
Another episode stars the excellent Jack Klugman called, "In Praise of Pip". This story is not creepy or have an odd plot twist. It's a dramatic story about a bookie played by Klugman whose soldier son is dying in Viet Nam and his dad's wish to have been a better father and spend another day with his son.
It's hard to find a bad episode of TZ.