A quality silk line (as in real silk) has virtually no memory once it is well broken in. But that can take quite awhile in some cases. Phoenix silk lines are the lone exception to this (in my limited experience thus far) and are ready to go right out of the box. But you pay for that level of finish.

Aside from real silk, my experience (in cold water fisheries) is that all of the plastic lines will retain some memory, but I've had good luck with the Cortland Sylk lines (which Lotech suggested), and the Rio Trout LT lines. The S/A Supra lines also seem to be a pretty good line in this regard, and are a bit less expensive.

Having offered that, I'm not sure a different line is the solution to your problem. My guess is the line you have is likely to be adequate if you are getting the fish to "sip the midge". I think all of us have fish that can frustrate us in this regard. But for me, improving my abilities, and developing techniques to overcome the angling challenges I face is probably the real solution to them. Despite the fact that I often buy another piece of equipment in search of the answer. Whether it be a different fly, or a whole new rod, reel, and line. Oh, and don't forget a new furled leader, and...

---David