Some people focus on (pun) the ratio of the front sight width to rear notch width, but I think the actual measurements are important, as well. Some people prefer a 1-1-1 sight picture, with the light bars on either side appearing to be the same width as the front. My preference is something closer to 1-2-1, with the bars about half as wide as the front sight.
I have a hard time hitting a point, when you can line up ten of those points side-by-side on top of the front sight; the sight has to be not much wider than the target, or aiming point on the target.
For "action shooting", .10", and even .09" front sights are common, with a .125" rear, but I like those combinations for precision shooting, too. It's easier for me to gauge the width of the "light bars" on either side of the front sight, than to try to align the edges of of a front sight and the edges of the rear notch, which is a common set-up - the front sight almost filling the rear notch - on stock pistols.
Ultra-wide notches, combined with wide front sights, appear to be a response to failing eyesight, rather than an actual aid to aiming.
I prefer a .10" front and .125" notch (and the notch deep enough to see the entire front sight in the sight picture), for just about all handgun shooting with a "service pistol" sized gun, if it's my call to make. A very long sight radius would indicate a wider front, and short sight radius, a narrower front.