City Walk :
Red Oven- Good quality pizza at pretty affordable prices. Probably just behind Sal's at Portofino in terms of best pizza at UOR.
Marley's- They have some good Jamaican cuisine. I enjoy the cajun chicken sandwich served on Coco bread, which comes with Yucca fries. Delicious.
Hard Rock- I really enjoy their burgers. Not everyone is a fan of the tourist vibe of the place, but everything I have had has been very good.
Antojitos- I have only been there twice, but it has been very good both times. I have tried their enchiladas and their fajitas, which were both tasty. Others have had issues, but I would recommend this place.
I would say Bubba Gump, Margerativille, and NBA city have average to decent food, but I would check out the places I listed above first.
Islands of Adventure:
Mythos is hands down the best restaurant in the park. You can't go wrong with anything at the place.
Burger Digs is probably the best quick service place at IOA, which isn't saying much as it doesn't have much competition. Their burgers have been well cooked every time I've gone there.
Three Broomsticks is pretty good as well, as long as you don't go when it is really busy. I had their fish and chips which were good, but there weren't enough fries too my liking. Would still recommend it though.
Universal Studios Florida:
Sit Down
Finnegan's- Traditional pub fare, but always well prepared. I particularly like the complimentary soda bread, served with a sweet apple dipping sauce. Mmmm...
Lombards- The best place to eat fish in the parks. The head chef is the same one as at Mythos, so the food is up to par. Their fish tacos are the best option on the menu. Get it.
Bumbleebee Taco Truck at Springfield- Imo the best new addition at Springfield. While pricey, all of the options are very fresh and full of flavor. Their beef tacos are the best.
Onsite Hotels
Sal's- Even if you aren't staying at Portofino, Sal's is still well worth the visit. Their pizza is incredible, among the best I have had in this country. The Salvatore-mozzerella, pepperoni, mushrooms- is the go to pick. Scrumptious.
Have heard great things about The Kitchen, but have yet to try it. Might be worth a visit.