I have dined at both several times and if I could only go back to one it would be Narcoossee's every time for me, but I think it depends on who is in your dining party. Topolino's is pretty but feels more like a large ballroom at a nice hotel, so might be good if you have a bigger party or some younger kids. Narcoossee's is more quaint and charming, so might be better for a couples dinner. I have ADRs for both booked for our next trip, but honestly wouldn't go out of the way to eat at Topolino's if we weren't staying at the Riviera. If you have any food allergies, I find the menu at Narcoossee's more accommodating as well. Enjoy your trip!