We have been playing a lot with level lines for the past 2 years. It has been a big experiment for us trying to figure out what we liked to fish with and what would work the best all around. And the answer is: It depends! We tried tying some with tapers, using several different materials for one line, multi colored, etc. But in the end, we feel like a fixed length level line in Hi-Vis size 3 or 4 is the right way to go.
In addition to picking the length (10.5 ft, 13 ft, and 16ft) we are offering a size 3 or 4. The size 3 line cast really well with the Sierra Rod and Sawtooth, as well as the mini rods. It is a very delicate presentation and lightweight, small diameter line. The size 4 casts extremely well with all of the rods, and cuts through wind a little better, but you are sacrificing some of the presentation. It is a slightly larger diameter.
The hi vis makes it really easy to see and track your fly. We have hi-vis Orange and Chartreuse. These lines fish subsurface really well if you are using Tenkara flies, they fish dries really well, and they can also sink for fishing nymphs. These lines will retail for $14 but are on sale for a brief time just so we can get feedback and see how people like them. Go HERE for more info.