Any winter steelhead but a buck taste's a little better but you have to have a keen fish taste to tell the difference. I think a female uses more energy making eggs that takes away from the meat quality.
I heard that summers pack on more fat than winters because they stay in the system longer than winters kind of like why springers taste better than fall Chinook. Springers pack on more fat because they used to have to go upriver much further. I haven't eaten a whole lot of summers to say one way or another but I do love my winter steelhead!!
I say an early Summer buck is the best tasting fish. The summers have more fat to sustain more time in the river and everyone knows that fat = good. The water temps are still cold so you still get that fridge effect. Plus somehow all the jumping they do makes them taste better.