The authority on leaf spring rates are the guys at ORD. All the off the shelf leaf springs tend to be stiff. Some are better than others but the only guys with really nice riding leaf springs have gone to custom ORD springs. It will cost you more but you will get just what you want.
I have both Tough Country and Skyjacker softrides in my trucks and they both ride stiff.
I have both Tough Country and Skyjacker softrides in my trucks and they both ride stiff.