i have used....
xspot
easton g-pin
bohning pin
big G
all nocks are orange in the offerings.
the diameter of my serving at the d-loop is .098 +/- .005
for me, the xspot large would fit too loose so i tried the smalls and those were way too tight, good for a string of .088-092. with the large, the ear's grip wasnt there. if i ever so lightly tapped my string, the arrow would fall off. best suited for strings with a serving diameter of .100 to .106
easton G-pins work great, their only disadvantage is the cost.
the bohnings work the best for me. a nice soft click and the throat is loose, but not sloppy. slip pressure of the ears is just about perfect for my string. they are relatively tough but they also show damage quite well.
the big G large are just too loose. they dont seem to have any grip between the ears. they would be better suited for a serving diameter of .102 to .105
these are just my observations with what i have tried. others may have better luck with the others but for me, the bohning pin nocks are the best for me.