Better -- well, that's somewhat relative. It depends on the kind of dining experience you want.
Whispering Canyon -- loud, rowdy, fun, loud, pony races for kids, skillet food, loud -- get the picture? Actually, WC for dinner can be fun. However, the atmosphere is very casual and often very loud. The servers run pony races for kids through the restaurant. Some servers bounce the serving tray holders on the floor (sounds like a horse, I guess). Food is average for the price. It can be a lot of fun if you get into the spirit of hooping and hollering with your meal.
Artist Point -- quiet, romantic, set apart, wonderful food, fine dining with a price tag. AP is a great place for a delightful couples-only dinner. The food is very good and I think the service is also very good.
The two restaurants are as different as night and day, so a lot depends on what kind of dining experience you want. As far as food goes, AP is definitely better. As far as sheer fun, WC gets the nod.
If you want a wild dinner with adequate food-- choose WC.
If you want a leisurely, quiet dinner with food that will awaken your taste buds to new experiences -- choose AP.