I think my all time favorite changed nearly every year over the decades.
At first, I think it may have been the test pattern that came on in the afternoon before the Howdy Doody show, then Howdy Doody became my favorite.... even to my being one of the oldest members of the peanut gallery. (We vacationed in NY, and got tickets to the show.Oldest meaning I was about a 9 year old among 5 and 6 year olds.)
After that, Captain Video was one of my favorites, followed by Science Fiction Theater, and shows like the George Gobel show, Jack Parr, Jackie Gleason show, Ernie Kovaks show, Milton Beryl, I love Lucy, Steve Allen show, Maverick, Sugarfoot, and yes, Gunsmoke. Also later shows such as the Smothers Brothers, the Avengers, Laugh-in, My world and Welcome to it, Bob Newhart, the Prisoner, etc, etc. Too many modern shows to mention.
I think over the years I've had HUNDREDS of favorite TV show of all time. Right now, my favorite is MONK.
Almost forgot... The Lone Ranger and Red Skelton, Perry Mason, and later Get Smart, .