Just a note. I’ve been fly fishing for about 4 years, now. In the last trip or two, I’ve been having trouble getting close enough to tails to get the fly to them… more trouble than usual. I thought I was being to noisy or casting a shadow, or other and the fish were going quiet. Well, yesterday, I think I found part of my problem. My fly line was original. I swapped it out for an Orvis 8 wgt WF floating line and got another 8 yards or so of casting distance. I kept the old line clean, but, it apparently was not sliding through the rod guides easily anymore and I was losing distance. Since it happened slowly, I did not notice until I swapped it out.
Short version: if you’re fishing 4 year old fly line, replace it.
Along the same lines, I like to clean my lines and then apply a line dressing or armor all to the lines. The dressing really makes the lines slick and shoot much better and also keeps the lines from knotting up when you are trying to shoot lots of line out.
I used to clean lines with Armor All and then had some trouble with a new Scientific Anglers line and sent it back to them. It seemed to develop cracks really easily. I told them I cleaned it and used Armor All and they said that was the problem, the armor all is bad for newer fly lines. This was 5 years ago. They sent me a small bottle of their cleaner and it worked much better on the new lines.
I have heard that about the armor all before but haven’t ever seen a problem with it on my end, but better safe than sorry i guess. As for the best, I like Russ Peak’s line dressing. When I worked in the shop in Wyoming this is the one everyone used and we had a couple guides that were on the US flyfishing team and were sponsored by about everyone so I will defer to their judgment.