Oxybenzone (ingredient in some sunblocks) and DEET potentiate skin absorption of each other, whereas picaridin and oxybenzone absorption is unchanged or even inhibited when used together. https://www.ncbi.nlm.nih.gov/pubmed/21155391

The EWG piece is really worth reading, because it highlights how "what's the best insect repellent?" is the same kind of question as "what's the best bike?" First you have to understand what you want from it, and only then you can figure out which products can best do the job.

Armed with some more knowledge of the mosquito species in the micro-environments in my area, I bought something with picaridin, only because I want to make one more trip to the blueberry patch before the season's over. But I don't anticipate using it often. Bite Blocker works fine on everything *except* those Asian tiger mosquitoes.