Since I have been fishing Tenkara I have mostly fished with parrallel lines that we, Tenkara anglers, call "level lines". They are a little more demanding to get good casts for a newbie but allow, in my opinion, better drifts because their similar diameter through the length.
However I have nothing against other types of lines and I recently had the opportunity to test a tapered line called "Soft Tenkara" by the Fujino company.
This line is not made of fluorocarbon but of nylon, it is adaptable to more diffenrent techniques than fluorocarbon that is unusable for dry fly fishing. For me who only fished wet flies I thought that using a nylon would rather be an inconvenient but once I fished with this I realized that it made me fish differently because the fact the line is not designed to sink required a different approach. It is easy to keep out of the water which is good to obtain good dead drifts.
The major problem of fluorocarbon lines is that this material does not take the dye very well and most of fluorocarbon lines have a too light stain. With the Soft Tenkara you have a perfectly dyed line that is clearly visible in all light conditions.
Regarding the casting the line loads the rod very well and one easily get clean accurate casts. I have tried this line with very different rods, from Tenkara Times Try 360 to Oni Type III and it did give excellent results.
I think that for anglers who do not dare to try level lines by fear of not being able to cast it properly the Fujino tapered line is a serious alternative. They will get easy and clean casts without major difficulty.
This excellent product is available in five different lengths from 3.3 to 10 meters. The only downside I see for someone who is used to make his own lines is the fact that the line length is predefined.
You can purchase this line through the European dealer Tenkara Centre UK.