Best Disney owned, I would definitely give that to the NY Strip at Coral Reef. After that, I'd go with filet at California Grill. I've dined at Yachtsman Steakhouse 3 times now and I have been overly disappointed in the steak there... it's a good thing they have a great dessert, though nothing was more disappointing than Jiko's filet for me. I like flavor, I like seasoning, chewing something bland has no interest to me.
For on Disney property, Shula's wins that HANDS DOWN! But they are also all over the country so if you have one in your hometown, I'd suggest going to that one and saving that dining spot for a Disney-only restaurant.