V1500 Cygni (Nova 1975) reached magnitude +1.7 at maximum on August 30th 1975, having been discovered the day before at magnitude 3.0. It faded very quickly after that – t3 = 3d (then the fastest Nova on record and still has, I believe, the largest amplitude of any known Nova ~19 magnitudes). I saw it myself, and the event put me on the VS path.
The brightest Nova ever recorded is V603 Aql – Nova Aql 1918, the ‘Victory Star’. This peaked at magnitude -1.4 in June of 1918, and you can still see it today in small telescopes, varying slightly around magnitude 12.0. I wouldn’t think there is anyone around now who witnessed this spectacular event though.
Gary