It’ll depend on what you are interested in when travelling. 
If you’re looking for culture and a fascinating city that has retained its historical identity rather than losing everything in the rush for modernisation, then Hanoi is for you.
If you prefer a more cosmopolitan city with plenty of nightlife and shopping, then Saigon would suit you better.
However, it’s not just simple because these two cities differ on almost every point – from food and culture to size, history, geography and climate. You can read in detail here http://insidevietnamblog.com/2015/02/13/hanoi-vs-saigon/
What matter here is that in November, Hanoi’ll be in the cool weather (18-26ºC), sunny and dry; SaiGon’ll be in the rainy season with high temperature (26-37ºC).
Personally, I’ll choose Hanoi. It’s one of the most romantic time here when all of the streets are full of yellow leaves, the weather is cool and sunny. You can wander around Hoan Kiem lake in an early morning, drink egg coffee in a local coffee and get out of Hanoi one day and enjoy Trang An river which is far from Hanoi only 120km. 
 

Hanoi in November

Tam Coc  boat cruise on scenic river
Trang An, far from Hanoi 120km