I still used 4 kinds of nylon cords which are shallow and experienced, but I will last long even if I hit stone walls and fences. It cuts into an appropriate length and is charged with a small size of crimp sleeve.
I tried various things, but I think that square type is the best as well. Although I do not know in the environment that sounds etc. I care about, the sustainability and durability of the sharpness are the evaluation points. I think myself that sharpness itself may be difficult to achieve with durability.