Here's a little blurb on YT about ergonomics in a folder.
Although it's about a particular Kershaw knife, I found his approach in analysis to be pertinent to most EDC type knives. It's a nice relaxing video to watch when you got some free time.
Here's a close-up on the choil of my Spyderco Chaperal. You can see how the handle and the blade combine to create the choil and that the choil has jimping (notches) which I like because it gives a better grip and feel to the hold. There's some jimping on the thumb hold too.