PE for The Sullivans ...
Toms Modelworks makes a set. It is fine and well done, but Toms does not relief-etch their brass. And they use a softer brass. I would rank it in a lower tier.
Flagship Models made a Fletcher set for the Tam Fletcher. Much of it can be re-used. Flagship uses a harder brass and does relief etching.
Gold Medal Models makes a very complete and comprehensive PE set. While originally designed for the Tam Fletcher it will do The Sullivans well. Hard brass & relief-etched.
Yankee Modelworks, John Sheridan has released some of the PE sets from the Blue Water Navy/Yankee Modelworks Fletcher kits as standalone products. They are excellent and well done. Hard brass & relief-etched.
L'Arsenal, Jacques Druel is producing a PE and resin upgrade and correction set for The Sullivans. I have two on order with shipcamouflage.com. It will contain correct 5-inch gunhouses with brass barrels - the ones in the kit are too small. It will contain correct 40mm guns - the ones in the kit are little more than sticks. It will contain correct 20mm guns - the ones in the kit are about 10 feet tall. From photos, the brass looks to be complete and well done. I've not touched the final product but L'Arsenal has a reputation for quality work, using hard brass & relief-etched.
My first choice would be any of these last three. FDlagship is good, but I think these three are superior.
The only Fletcher set I have never seen is the Eduard set