Which sunscreens on the market in the us offer the best uva/uvb protection and do you recommend physical (zinc oxide) vs. chemical sun filters?

Sun Block is better.: In order to provide full skin protection, a sun block should contain either Zinc Oxide and Titanium Dioxide. This will provide full protection. Also it should be reapplied often like every 2 hours when at the beach or the pool. Remember also that the higher the SPF, the more chemicals you will have in the formulation.

Which sunscreen: Zinc oxiide best and with least allergic potential. Most SPF blocks have titanium oxide which is easier to incorporate and less expensive, but there is still a 4% allergy rate to the later. Zinc can give a light palor to the skin but try Shisedo. The zinc block is the best but can be thick in some foundations and makeup. Use the sun wisely 11 am to 2 pm . Get your vitamin D early in the da.y

I personally recommend Zinc based sunscreens with an SPF of at least 30. There are Neutrogena brands as well as Zecote that should fit this description. Make sure to apply 15-30 mins before exposure...and reapply every few hrs.