If you're looking for kid appeal, go with Coral Reef. We enjoyed our lunch at Chefs and I think they have the better food, but Remy is about 5 minutes of interaction with an audio-animatronic on a wheeled cart. It is a nice bonus if you want to dine there anyway but not a reason to book the restaurant in my opinion. Coral Reef, on the other hand, is constantly changing visual appeal for kids and is great for keeping them occupied to have a nice relaxing meal.
We've always (as a party of 5 or 6) gotten second tier seating, which is great because you get a more panoramic view of the aquarium from that level and because you don't end up with strangers crowding you to see the fish close-up like can happen tankside. I think being in those booths makes for a quieter/calmer atmosphere than being on the main level, and we thought the atmosphere at Coral Reef was lovely.