They are different experiences. The Grand Floridian Cafe is a typical casual dining environment at a nice hotel/resort, with the traditional fare. Kono is a theme atmosphere with a theme menu, including the above described desserts.
If you are seeking the Disney Experience, then Kono is your best choice. If you are seeking a quiet break from the day, then Grand Floridian Cafe is your best choice.
Either way, you are at Walt Disney World!