I combine both ways of reading/listening to make it well in my exams but if i must pick between the two thwn i will definitely go for reading.
Reading notes that i have never been lectured on has not always been a major problem for me and most people i believe. You can easily understand them and still make a good pass in your exams. I think that is why at the higher institutes, reading as a tool of research is mostly used. Lecturers hardly say much and you as a student do a pile of the work by reading and trying to understand on your own because at that level that is what is expected of you.
As for listening, i for one enjoy listening to my lecturers but to be honest if i should depend on that to make it in exams then my chances are very slim. I easily forget it and to remember what i listened to is a little more difficult as compared to recalling what i read. So for me, if i was to grade my pass in an exam as 100%, 70% will be because i read and the remaining 30% because i listened.
So it is reading for me but i must conclude by reiterating that it takes both to make a complete student or learner.