I can't speak for anyone else, but I like a Bowie type blade, a bit wider at the front ( 1 1/4") than at the back (1 1/8"), 6" or so long...1/4" is plenty thick enough. It needs a clip point at least a third of the blade long, but not over half, and sharpened the full length of the clip edge, and no blood groove
It should have a very small top arm, not over 1/2" on the straight quillon, longer on the cutting side, maybe an inch or a bit longer.
A 5" long handle a bit wider at the butt end, either full tang or full round handle, hard wood or stag (or ivory/bone, though not as durable), is sutable. I also want to be able to fit it to my own hand after I get the thing.
Such a knife can effectively be used for fighting, butchering and skinning, cooking, and general camp chores. There's no such thing as an "all purpose" knife, but in my mind that would be close enough for my purposes, especially along with a good pocket knife.
I like and appreciate the file work, but am more interested in a working blade. File work is an attractive bonus.
A sheath of heavy russet leather or russet leather-covered rawhide with the cutting edge to the rear when worn on the left side, forward when on the right, with the top of the pocket (quillon height) at the top of the 2 1/2" gunbelt.
No tie-downs or retaining straps, no decoration, no Mexican loops. Make it snug enough to hold the blade against falling out too easily. I can always tie it in with a thing if necessary.
Like I said, I can't speak for everybody. I have a beautiful 8" blade Bowie that's about as practical as a barbed-wire jock strap. Just too long for anything but fighting or sometime machete duties.
There are those who have inferred that I am opinionated about things. I cannot dispute that for a second.