I don't believe the Breed has near as much to do with the meat, as does the way the calf is handled during the feeding/finishing process. Kobe beef is the concensus best by the greatest Chefs around the world, and refers to cuts of beef from the black Tajima-ushi breed of Wagyu cattle, raised according to strict tradition in Hyōgo Prefecture, Japan. The meat is generally considered to be a delicacy, renowned for its flavour, tenderness, and fatty, well-marbled texture. I've had it Kona, HI, straight from Japan, and didn't care for it; way too much Fat! However, this process, with far less restriction, may work wonders for the outcome of a great steak from most any breed.
I've fed for personal use several different crosses, and all the way to purebred Hereford, Simmental, and Maine-Anjou. The Best Beef ever came from a Purebred Maine-Anjou Bull calf, Draftpick X a FR Magic X Stinger cow. Needless to say, this was way before I ever heard about PHA or TH. The calf was born unassisited, crippled in his front legs, and double muscled. He could walk, but never traveled more than about 10 steps at a time. I weaned him from the cow at 30 days, and started him on our Show Ration. He always had plenty of fresh, clean water, but never ate much hay. He would easily handle 25-30 lbs of grain daily from the time he hit 200 lbs. I got him all the way to 1150 lbs(13 months old, still a bull) when I decided I couldn't load him in the trailer if I let him get any larger. This Beef was marbled just right, tender, jucy, and Red. Even overdone, it was still incredible! To this day, I believe the all grain diet from a very early age, very limited movement, and the double muscling all made for the Perfect Beef.