"Carnivale" is a good shout if you like Twin Peaks.
Another one might be the original "The Prisoner" series, but you might already know that.
A severely underrated show is "The Leftovers", at times absolutely brilliant, a lot of things stay mysterious and up for interpretation.
My personal favorite show of all time is "Mad Men", which is something entirely different, but so well written and detailed that you can watch it again and again and obsess over it.
The Prisoner (original series) is fantastic. It was groundbreaking at the time and still a great watch today.
I'm personally not so keen on Mad Men although I understand why it appeals to a lot of People.