Both are good strains. The White Widow is 70% Indica and 30% Sativa though, and the NYC Diesel is a Sativa dominant strain; so the white widow is more of a stone high, while any diesel strain is usually a more cerebral high.
I lived in The Netherlands for a while and tried about 12 different strains of weed. The average THC Content of Skunk weed there, which is nothing special, is 18-19%. Orange Bud, is about 15%. None of the weed there is considered even mids. I would state that Schwags/Commerical weed is about...