Many as Shepley, use the knots of the loop for the nocking point for the arrow: this puts pressure on the nock of the arrow as the bow is pulled. Others tie a nocking point & etc inside the loop.

What is the most stabilizing for most people?

I like and use both systems (tie ins...no brass). The nice thing about using the tie-in nock points inside the loop knots is that if you need to change the loop, you don't need to worry about getting the nocking point height correct again. It does add a bit of extra weight though where you really don't want it.

I tend to use the tie-in nocks on shorter axle to axle bows as a loop knot can still pinch the arrow nock, and I use a standard loop as the bows get in the 35" range and longer.