I like a small diameter punch with a fine tip. I do a lot of aluminum and line up most holes with a coaxial indicator as most of my stuff is a CNC tool of some sort and accuracy of fit is always welcome.
I like the tip to be able to find intersecting scribed layout lines with ease. My last layout resulted in the boring of a 1.502 inch hole only .001 of an inch off when measured. It was for a stepper motor mount on the X axis on the mill in my avatar. I can live with that.
Good layout and the tooling to do it is essential for a good finished product, count a good center punch among those tools. Nothing is worse than just finished parts that don't fit.(Been there, done that.)