
Obviously wild fish (which for me is the same than HiQuality in Flyfishing), for several reasons. Actually so many I can only think of just a few to place here right now.
They are "hard-to-find" now these days, and therefore the places they still live in are marvelous. They feed on relatively non-contaminated-"wild food", also. So, the flies You need to try to "decieve" them are usually not so common patterns, need to learn from the specific place, and the combinations are endless.
The usual behavour of a given species varies so much often than foreign species "thrown" into an artificial lake.
You can learn so much, and add so many tips to your "knowledge data base", in just one fishing trip. I mean also with this statement, things learnt that almost no one notice them to putīem in a book.
I could keep writing all night, all weekend, all week...
Letīs see what the rest comes up with!