I first learned about clear nail polish as a fray stopper when viewing a video by Elly Sienkiewicz. I figured if it was good enough for her I would give it a try. She used Sally Hanson because it was the least expensive. The only problem I have found with nail polish is that the bottle of polish drys out and get thick rather quickly.
I now use Fray Block because it dries soft and does not show on the front if I accidentally get too much.
I have never seen Sew Secure.