My ratings are admittedly colored by the fact I am a Southern boy.
I have (a few times) tasted Walleye and it could possibly make a run for the top spot, but I just don't have enough experience to make that call. Trout seem to have a good taste if propperly prepared, but are much too soft-fleshed (mushy) to make the top list.
Most people who say they like fish.....really don't like a "fishy" taste. For them Crappie may be prefered due to it's firm flesh and mild flavor.
For that matter Largemouth / Smallmouth Bass are in the same catigory and you get the added benifit of a great feeling when cleaning them. Make sure you are close to a dock favored by the fanatical catch-and-release crowd and openly clean your catch. The look on their faces is worth as much as the filets.
Great flavor is had in Pike, Buffalo and Carp.....but the trouble with the many tiny "Y" bones takes them out of first place.
Over-all it's got to be catfish. Not just any catfish though.....they are different.
Any catfish living in still waters (lake, pond, ect) is inferior to one caught in a flowing river. The fact these have to "work for a living" makes their flesh so much firmer and tastey.
Pond raised catfish are the worst of the lot as they not only have the disadvantages of any still-water cats, but also are fed pellets that take away the true "catfish" flavor. Maybe that's why so many prefer them because, as stated before, many who claim to love fish really don't like the fish taste.
Also eleminate catfish caught in most tailrace areas in rivers as the constant flow of injued baitfish allows them to simply sit on the bottom and eat without working...makes for a fat, soft flesh.
Wild river cats are rated as such......Flatheads are best. Always firm fleshed, even if of tremendous size. Guess it's because they are true preditors and eat alsmost exclusivly live bait.
Channel cats.....also firm fleshed and seldom so big as to get "fat". Flavor is milder than Flatheads and Blues, but still difinitely "catfishy".
Blue Cats.......under about 10 pounds. Great taste and if caught in a free flowing river firm fleshed. Over 10 pounds or so they begin to get fat and soft and once over 25 pound or so are as bad as still-water cats.
I love bream also, but small size means many, many fish are needed for a meal. However, if you run into ones big enough to filet (3/4 pound or so)....they are great.
Just my opinion, but gained over 50 years of eating everything that swims. By the way.....worst you'll ever eat are Grinnel unless eaten right out of the grease. Once they start to cool at all.......are almost inedible.