Fine Round Rubber Leggs are a critical now days on many patterns. They add lots of lifelike wiggle. They work well tied in X style on dry fly patterns like adult stones and tied on the side on your nymph thorax's. We also make our own now that have been hand barred. We call them Tarantula legs.
Either one will give many of your flies a distinct advantage.
Caution...do not store them in direct light. Like a rubber band...they will eventually rot. If this is a issue then look at our silicone legs we call Sili-Leggs. They to come in a ton of colors, barred and flakes.
Similar to Wapsi's Round Rubber, sili legs, or Harelines Grizzly Barred Rubber Legs fine.