You'll likely get numerous recommendations, and every restaurant will have its detractors (even V &A, though those are admittedly rare). If you're truly looking for one or two to book, just look at the menus and start there. I would never say not try a place if you think you'd like it, though there are a couple to which I'll likely not return. However, your question asks "what is your favorite signature dining experience?" not which ones I didn't like. To wit:
Artist Point: There are several reasons, among them being it holds a special place in mine and my wife's relationship (first meal together on Disney property, site of our wedding reception dinner); the ambiance is superb and romantic; and the food is usually excellent, as is the service. We've never had a bad meal there in nearly a decade, though we once had less than their best, and in that case, though the problems weren't huge, the manager more than made up for it. We go every time we visit, though we also do other signatures. AP, however, is one we simply won't miss.