Right front. Thats the way I learned over 40 years ago. I change every bike I keep to that configuraton, which presents routing issues with side pulls with the cable on the right side. I rode motocycles for a number of years and learned to NOT panic with the right front. Periodic hard braking to understand the limits, sets me up for successful brake control and expectations of results. The practice works for both left or right for the front. Being right handed has something to do with it too as that is the side I do most of my precision control, writing, shooting weapons and cameras, tool selection, ignition key, painting, turning fastners to the right to tighten, shifting (including front rings on DT shifters), etc. My right fore arm is even bigger than my left! So I like to play to my strengths!

I took a break from bikes for 30 years and during that time, the preferred front brake control moved from right to left. Don't know when, my suspicion is that it was gradual or I was not aware of left/front controls on other bikes. My early bikes were 3 spd English "racers" and the rest were center pulls until I came back.