Either is great, depending of course on what you want to shoot. Big Sur has amazing land/sea scapes. Plus there are tons of little beaches for you to stop at, and explore the tidal pools, look up at the cliffs, etc.
I recommend this site
for great information on it. He breaks down the trip, showcasing interesting sites by mile marker (the most convenient way to know where you are on Rte. 1). Be sure to check his description of how to read the mile markers -- it makes a huge differnce.
Don't drive Rte. 1 at night if you are trying to find anything. It is a wild windy road, and if it gets foggy, it can be a rollercoaster.
Point Reyes is also beautiful, but realize that it is at least an hour north of San Francisco, making it 3 hours north of the most norther tip of Big Sur (Carmel), in easy traffic. With traffic, add another hour or two.