When considering the 'best', at least for sunscreens, it's important to consider where you're buying, and why you're buying in that market.
The FDA is far behind other nations in sunscreen ingredient and labeling regulations.
US market sunscreens lack options for ingredients, which limits the effectiveness of the product, especially for UVA (the cancer causing kind) of radiation absorption. They also are held to looser standards as far as how much UVA is blocked. "Broad Spectrum SPF50" doesn't mean SPF 50 for both UVA and UVB, it means SPF50 for UVB (tans you) and some unknown degree of PA for UVA (cancer causing) rays. Additionally, because of the limited ingredients, sunscreens tend to be greasier and not stay on the skin for as long, increasing the risk of a negligent sunburn.
If you are relying on a sunscreen or sunblock for skin protection, it is a very good idea to look into non-US market sunscreens. Non-US (European and Asian, mostly) market sunscreens tend to be much more effective, longer lasting, more sweat and water resistant, and more pleasant to wear.
Essentially, look for a high SPF (>50), a high PA factor (PA+++ or PA++++ is the usual goal), and good water and sweat resistance. Read reviews. See what other testers say, and see how the product is labelled. Reapply it frequently. Don't buy US market sunscreens, often brands has a US and non-US market formulation. The US market version is hamstrung in order to pass FDA regulations.