Think I fit into that category of fly fishers who have over a period of years tried different methods of line to leader attachment, and a host of different knots for anything I can think of for a fly rod/fishing set-up. After years of experimentation, trial and error, I've settled in for what works and fits my doings and needs best, especially in the field.

I'm a loop to looper for the fly line to the leader. What works satisfactory and the simplest for a line loop for me, is to tie a perfection loop (makes a smaller knot then a overhand loop) at the fly line end, and then cover the knot with a short piece of electrical heat shrink tubing (maybe 1/4" long), gently and carefully heat it over a 60wt bulb so it shrinks dcown nice and tight. So far, no damage to the fly line that I can see, but to make sure the line's coating was not effected, i use some silicone line dressing on the connection afterward. Makes for a tight loop that glides through the rod line guides without hanging up. The heat shrink tubing I use is 3/32" dia and has a 50% O.D. shrink.

For the leader connection, I use the standard overhand loop knot, and tie on the tippet with the old standby double surgeon's knot. For tying on a fly my most often used knot is the straight clinch knot. I know how to tie it right, in all kinds of conditions, and it works.