Is there a cipher that was considered the undisputed best before the computer age? (This is not supposed to be a discussion; it's either a yes or no.)
Please give a brief description why it is yes or no.
No, nothing is ever undisputed.
There is a cipher that provides perfect security (OTP) but that doesn't mean it is very practical if just for key distribution. So saying it's "the best" can be and should be disputed.
However, the answer the quiz master is looking for is probably the Vigenère cipher. I presume however that there must have been at least one person that had a doubt about the strength of the cipher.
There were many ciphers which were practical using pen and paper. I'd guess some could still be good enough for low-tech field operations (the already mentioned Vigenère cipher, The Straddling Checkerboard, Navaho code language, ..). They are not perfect and today could be broken, but I'd call them undisputed because they were successfully used and not revealed for a long time.