This route from Oxford to Blenheim Palace sticks to the Oxford Canal towpath for the majority of the route. It is very pleasant on a sunny day and much more quiet than the NCN route: you won't encounter any cars until reaching WoodStock Road.

However, note that the towpath surface can be quite rough at times, and you will have to share space with pedestrians. I still wholeheartedly recommend if you ride a hybrid or mountain bike and don't care about reaching your destination fast.