DEET is the most effective. Picaridin is only as effective as low-percentage DEET products, but it is an alternative...http://www.brms.com/nattrapel-8-hour...FVBgMgodhE0AEg
Citronella-based products are even less effective than Picaridin products.
Make sure your DEET products have around 40 percent DEET for maximum effectiveness...