I wish I had something exotic, I've been meaning to try a few different variations. I use default static, mainly because the crosshair gap is closest to my preference from the default menu. I've been lazy and got used to it, I might try making something cleaner soon. As you say though, it's completely subjective as to what feels comfortable for you.
Things that you'll notice are quite similar amongst pro players is that they generally have low - low/mid sensitivity, should result in more consistent aiming, muscle memory and accurate movement. Also no mouse acceleration, again for consistency.
They also generally run lower resolutions, many regard this as placebo, but it does make frame rates a bit more stable and people often comment they find spraying slightly more controllable and models seem to appear slightly larger.
I have personally always used native res for years, recently switched to 1280x960 stretched and find it helps ever so slightly. I had to adjust my sensitivity a little to accommodate due to the aspect ratio change. The only thing I miss from native res is how crisp everything looks.
