To kick things off I will start with the one I have found to be the most consistent taker of trout and grayling, on the dry.
It is a pink posted ( for Phil's benefit ) parachute fly with a light yellow dubbed body and a small red thorax, tied with a badger hackle.
Not only has it pulled fish up from nowhere, but I have cast it to both trout and grayling on the rise, and nine times out of ten it has worked.
I also find it a fantastic fly to see, as my eyes get worse.
Fished in a scum lane or fast water on the Eden and the Clyde, it has been invaluable to me.
Fly in my eye, Paul ties a mean one and has been very generous to me with them, as I tell him I can't tie them as well as he can.
Mind you I tell a few people that, and it usually works.

I can actually tie these quite well now, and they are simple, must be if I can do them.
I have caught plenty of fish on other patterns, one being Phil's BWO, but this is without doubt my confidence fly.
What's yours?