I’m a black circle around the number and a line through the pro v, which also help me as a lining up aid. ️‍♂️

Interesting discussion. I do a 360 degree line like a few others have mentioned (am hoping this becomes a standard OEM option on the balls).
I also put a filled circle of dots using the dimples, near the logo on either side as pictured. I find this isnt so common a mark, so I'm unlikely to find a similar marking on a ball near where mine might be lying in the rough or penalty area

A simple black dot over the “T” in Titleist.

My mark of choice is a NEON YELLOW sharpie. I color the number (always high #'s) and put lower case initials under TITLEIST

Dot next to the number and 3 small dots next to the model stamp

One simple dot under the number, usually with a green or blue sharpie.

Red line under my # 4 works for me.