I prefer channel cat but some of the others are good too. It depends on size and water quality. Flathead get pretty tough and strong flavored when they get big. Most catfish do IMO but at least hot sauce helps with the taste. I seldom catch small flatheads.

Blue cat are not very popular around here for eating. Around here blues are basically the same as a white catfish but come from a different area. Soaking any of them in buttermilk can help out a lot to improve flavor but its never as good a small one fried whole. IMO the bones add a nice flavor when cooked whole but they still need to be fairly small.