It is impossible to tell you what is the "best" because everyone has different needs. I have, also, been looking for the "perfect" bag for me and have settled on this one which may not fit your "needs" but it is a lot easier to wear on an all-day outing. The only drawback to it for me is no place to pack a rainjacket but I figure I could roll the jacket up and bungy cord it to the shoulder strap if needed. Of course one could also purchase the light poncho type for about a dollar and just put it in the pack. I own the expensive type of rain jackets and never carry them because of the size and bulk. When winter fishing I will wear them as a wind break to help keep warm.
I like this small pack and I will probably keep "tweeking" it after each trip. It holds everything I need and is not overly heavy. You will just have to see what fits your needs and this is what I am presently using. Just keep in mind that the larger a pack is, the more you will put into it and the heavier it will become. Try just putting everything out on a table that you use regularly on a fishing trip and try to come up with a pack that will carry it and nothing more. You will be surprised what all you are carrying and not only forgoten but never used.
http://www.smallmouthflyangler.com/p...01_f.php#specs
Warren
Fly fishing and fly tying are two things that I do, and when I am doing them, they are the only 2 things I think about. They clear my mind.