I think sun cream is better than a physical shade for a few reasons:
1. You have to stay under a shade, but wearing sun cream you can roam anywhere.
2. If travelling beyond your back garden, then you have to take it with you, and it's not aways easy to fit in the car or lug around.
I think the best sun cream is UltraSun 50, which is also an anti ageing cream and moisturiser. It is also water resistant and lasts all day, so you don't have to keep topping up.