I'm not sure where the best seafood is but
My DH had an excellent Salmon dish at Tutto Italia in Epcot
and I had the pasta with Crab meat and it was delicious.
One thing that's nice about WDW is that at almost every
sitdown restaurant there is a Seafood choice and every time
we eat TS I order the Seafood choice and they have all
been very good--fresh tasting seafood.
The only seafood place we have eaten at was Fulton's and honestly we hated it. It was terrible. Maybe they were just having a bad night - who knows but I was with a party of 11 people and I don't think anyone enjoyed it.
Flying Fish is great. It's a bit pricey but what isn't? Plus the Boardwalk is a great place to hang out after. Street performers, carnival games, ESPN, Jellyrolls and more. You can work off your dinner riding a surrey, the hills are a killer. Watch the fireworks from the bridge. Do you think I like the Boardwalk?
I asked the same question 2 days ago and most of the responses recommended the Flying Fish. I haven't eaten there, but I have eaten at Fulton's and it was good, not great, but good.
Just a heads up, Fultons isn't on the DDP and Narc and FF are both 2 TS credit meals.