Here's an a few pages about knives from an old (1929) American Book that is packed full of good bushcraft lore, though it wasn't called that back then.
Being a lifelong outdoor enthusiast, now in my fifth decade, I've always carried a knife - even in gradeschool, probably started carrying everyday in second grade. Started out with a Barlow Pattern folder, then carried a Boy Scout knife for a few years, then a Swiss Army knife for a few more years before deciding I prefer knives to be knives, not can openers, saws, toothpicks or screwdrivers. From that point I began carrying Muskrat Pattern until I was into my twenties and then a single locking bladed knife in one form or another since. While hunting I would typically carry a fixed blade, usually a Western W83 and then later the larger W84. Never had much difficulty quartering an Elk with a folder but a fixed blade was superior and easier to clean afterwards. I did carry a Ka-Bar back when I was a Boy Scout - back then they were very inexpensive at surplus stores and it was the only fixed blade I could afford. Still have it, worked great as a chopper and could handle all the abuse I put it through.
Most recently I've been inspired by many on the Bushcraft forums to try and make my own knives. At the moment I've only just begun having modded a few Old Hickory (a fairly common and inexpensive American Kitchen Knife Brand) Outside of the Kitchen I haven't tested them on any big game yet but I have every confidence they will perform well. The steel is very good and takes and holds a keen edge.
Eventually I'd like to make my own knife from scratch but being on the steep part of the learning curve I'm hoping to make my mistakes without paying too much "dumb tax."
Last month I carried one on a five day Bear scouting trip. I used it every way I could think of and was very impressed by its performance and abilities. It is a bigger knife than I typically carry but didn't find it to be awkward or burdensome at all. Here's a picture of me walking up to my game camera wearing it in.
My own ideal is somewhere in the 3-1/2" to 5-1/2" depending on what I need it to do. My guess is that would work well in Europe too.