Depends on how I fish, but my main line is 4-8lb Nanofil which no abrasion resistant whatsoever then I use hybrid 6lb leader. Under bobbers and cast on to cover I will add another 6-10” Izorline leader on top with swivel (smaller diameter than hybrid) just to preserve my whole bobber rig in case of breaking off.
I either use double uni or Crazy Alberto for connections knot. Uni knot for everything else.
Note: on my casting setup, i don’t care for leader, less headache, less knot.