Do you carry your modern knife with the tip up or down, why?
It's a good question, but calls for other questions to dial in a good answer, particularly (for me) what size is the knife, and which pocket is it carried in? You have received some good answers already, and here is my answer.
For me, the pocket the knife is carried in is one factor that affects optimal clip placement. I like my knives in rear pockets tip down. I don't carry front or side pocket any more, except in track pants. But because the track pants are loose enough, when I take the knife out, I sort of pull the knife a little rearward in order to get a good grip. Length of the knife handle also. I like larger blades, like the Resilience, which is my main EDC folder, and I find that with the clip tip down, ergos are not compromised much if any.
My Tenacious, which is my secondary EDC folder, gets carried in my left cargo pocket, to the right of my phone. Truth be told it serves more to keep my phone vertical than anything, and it doesn't really get used much. Strange, I know. But, when I do use it, tip down is easier to deploy the knife and open with minimal adjustment required. Not so with tip up.
With tip up, on the other hand, I have to adjust my grip for both knives. And when I change the clips to deep carry, that changes from "ergos are not compromised much if any" to "ergos are hands down better than all ways except clipless". Again for my knives, in my hands, how I use them. So they are better for me like this than any other way:
