Deer hair can be very effective , probably elk is best but you need use a fly tying Combe to remove the fluff , normal method is to cut a small section from the skin Comb out the fluff and put in a hair stacker to even out if required ,

Having said all that , the best I have seen is the stuff some of the Italian guys use " Sea Grass" but you need to go to Salerno to get some from the beach . Great excuse to go there