Cobra jets are probably the better of the two, however if you drive your car primarily on the street I would go with the BMR springs. I havent installed my springs yet but initially I started with K springs but now have the BMR sp009's waiting at the house along with D specs.
What's wrong with k springs?
I daily drive mine with 13 cj springs. I believe they have helped with traction.
I dd in my 13cj springs, and i like them.