Kids' favorites over the years:
Bubba Gump - enjoy the interaction with waiters, quiz, mascot, and theming
The Feast at Three Broomsticks - love the food - ribs, chicken, potatoes, corn (comfort food)
Toothsome love the elaborate desserts and characters (check for last minute cancellations)
Margaritaville - love the theming and volcano
Royal Pacific Pool Bar - love the chicken nachos
The Kitchen at Hardrock - love the food in general and the desserts
If your kids like tater-tots, the Green Eggs n Ham restaurant in the Dr. Seuss area is very good, and I'm sure getting green eggs would be a novelty most kids would find cool.
For fun theming, the Circus restaurant in the Dr. Seuss land and the new minion cafe would be good options to look at as well.
There are also character meals somewhere. I've never done one before, but it might be something you are interested in.
This year we stayed at Aventura and the food court options there were great. The kids would have loved it when they were little as everyone could have split up and gotten what they wanted. Also, loved how small and close together it all was and the lack of long lines. Plus, that it is all cooked fresh. I don't remember liking the CB options as well, but it's been awhile.
Also, be sure to check out fun snacks and desserts around the parks. We've always enjoyed the treats in the gift shop the Trolley Train ride dumps you out in. There are lots of fun themed things to try in the HP areas besides butterbeer. You can get Dole Whip in both parks which most people don't realize, and there are many other character specific treats spread around.
Honestly, we've never really had anything awful at Universal. Overpriced, yes, but bad no. There are tons of great options from hamburgers to pizza to pasta to seafood. There's a large variety of kid friendly foods around. We struggled at Disney with the kids because so many restaurants offered "upscale" type dining, and my picky eaters were not familiar with 99% of the menus. Even kid's menus at Disney had few things they recognized or would touch, but we never had issues at Universal. Kid friendly familiar food everywhere.