Surely it’s either Mastermind, or Who Wants To Be A Millionaire ?
I long ago abandoned
Mastermind for two reasons:
(a) The question-masters continue using the silly catchphrase, "I've started so I'll finish." Everyone knows that a question interrupted by the buzzer is continued and may be answered. I'm all in favour of tradition, but that "joke" went stale long ago.
(b) It's impossible to ensure comparability of difficulty in the special subject round. However you design and calibrate the questions, "The Biggest Hits of Freddie and the Dreamers" is going to be easier than "The History of the Universe".
Millionaire? It's OK, but it's too slow for me. I would guess that an episode of
University Challenge or
The Chase gets through five times as many questions.
But we all have different preferences. Also, how many quiz shows can any one individual follow? In my case, a maximum of two.