Grand Canyon du Verdon South, Col d'Illoire
     photos by: Francis     
This is the exit at the western end, over the very sharply-defined Col d'Illoire which is like a knife edge, with a fine descent to the lake.

Both northern and southern routes are best at each end, with a less interesting section in the middle.
The southern route is very hilly indeed, and longer, but with ultimately the best viewpoints, while the northern route is much easier and still with excellent views.
There is no 'best' or 'worst' route, you have to do all three roads, though it may take several visits.