Most of my cases of M3, and I use a lot of different screws, depending on if I want something low profile like but needs a screw drivers or wrench, or something easy to remove without tools like knurlies.
For my two M2.5 cases, I really prefer being able to swap modules in an out without tools. I was using some allen socket heads which are just big enough to twist with my fingers at M3, but at M2.5 those are too small. The knurlies solved that problem and I will probably only used knurlies for my M2.5 cases.