Having used several store bought mono loops, and I cant say I have ever had one fail. I have come up with a different concept that I call true loops. I call them true loops because unlike most store bough braided loops that rely on the catching mechanism of the braided mono to hold the tag end, true loops have both ends secured.
I like to use 50lb gudebrod and a regular sewing needle to do the splicing.
1 Both ends are secured.
2 The loop is right up next to the flyline so you have better energy tranfer to your leader
3 they are very strong, I have lifted 40lbs with no slipping or breaking.