Totally depends on what you are fishing, but Swing4steel has told you about by far the most productive day in and day out patterns for most species in the fall. Those 2 alone tied in a variation of colours will catch you Steelhead, Salmon, Smallies, Carp and anything that would possibly take a fly. Now if you are looking to to swing, there are some traditional salmon and steelhead patterns tied on salmon hooks that will be a hit or miss depending on what they are feeding on, but are just beautiful to fish regardless. And on the other end of the spectrum for swinging, you have all your intruder/trailer hook style flies that will get better hooksets but is again a hit or miss thing based on a number of variables. Like Swing4steel said, good start would be egg sucking leeches and wooly buggers