No doubt, classic "spey" and dee featherwings for steelhead. I find them the most challenging, mine are often very ugly, but they have a classy look when I get lucky tying one. Plus the steelhead love them. Plus wets and soft hackles. I guess I have a thing for silk thread and floss!
Steelhead flies. Intruder style flies and tube flies. Some cool patterns are Jerry French's Dirty Hoh, Camo Squid, Ultra Squid, Skinny Hoh variants, Rob Crandall's Devil's Candy and Steelhead Nightmare to name a few. I also enjoy tying classics like General Practitioners, Undertakers, Coal Cars, and other variants on salmon iron hooks. There is just so much that goes into them and the precise placement of materials to effect the swimming action of the fly. They are engineered flies to extract every bit of movement and flow of the materials built into the fly. After spending 30-60 minutes at the vise to create one, you are left with a thing of beauty and a lot of pride. I then can't wait to see how the choice of materials reacts once in the current. As I tie them, they bring me to the rivers and runs of the awe inspiring steelhead rivers that I have fished so far that are forever burned into my soul.