To me the Chemdog #4 is the best of the bunch, I love the 91 and d, but the 4 has the perfect high for me, xcellent yielder, tastes really good, I like the 91 taste slightly better, and the d is last out of the 3 at least for me but any way these sound nice, might have to check em out some day. We made a few x's with our Chemdog #4 cut. Actually just burned some of our colt.45 aka Chemdog #4 x melvanetics nl5, and our dirty diesel aka ECSD(Chemdog #4 x bio diesel). I like our dirty diesel 2.0 a bit better, its bio diesel(ECSD x colt. 45). Pretty much anything the Chemdog #4 touches gets better.