I was once told that fish need to close their mouths to breath properly and that has seemed good advice so whatever you use I'd suggest poking the upper whatever as well. The metal snaps w/ chains are like anchors. The nylon snaps can be used individually on different length cords plus they are really light too.

The rope type are light and cheap but are compromised by pointy teeth in the short/long run.

Just don't string a big  'ol laker by the lower jaw and paddle around unless you want a picture of a really fat, dead, stiff, grey fish and unneeded exercise.