Freshwater = Walleye. I spent my teenage years in Southern Alberta and fished every slough, river, irrigation ditch and lake within 200miles of Medicine Hat. Fresh Walleye from the Oldman is second to none.
Saltwater = Alaskan Halibut. The spring and fall fish trucks use to come through town loaded with the latest catches from the coast. Salmon were good but the halibut slabs were heavenly. (great job, mom!)
I'd love to try Walleye. A great reputation for taste as freshwater fish go, almost always mentioned by folks "in the know" along with crappie. Alas, the only lake around D/FW stocked with a viable population of them? Wheeler Branch. But, they are a tough target.
Ah! Halibut! JackCaster nails it on the head for me. These fish are large enough to present thick slabs for cooking. And, what a taste.
For you catch and release guys still needing options:Icelandic Cod
fish sandwich or plate from Zeke's in FW ordered with okra and eggplant? You'll never eat at a Pappadeaux again. Zeke's is legendary, you never get over it if you need a dose of fried food. Habit forming, be careful. The owner is a great guy, used to be a bit like the Soup Nazi, but has mellowed with age.Halibut
fish sandwich from the Lake Athens Marina Restaurant: very good, great even.
The Bottom on Bluebonnet Circle in FW - Halibut
fish tacos. Dear God!Catfish
? Shrimp N Stuff on O street in Galveston, the old location. Even a half order is a big meal. This place knows how to fry fish. Cheap, too.