FnF is the knot I tie in mono for virtually all swivel/snap/hookeye connections.

I can be tied completely burn free.

I also like that the tag lays 90 degrees to the axis of the knot. This helps me to better secure leaders pre-tied with swivels/bead chains onto foam rolls without them coming unraveled.

My second favorite knot for the same purpose is the twice around San Diego Jam. It's a bit easier to tie when your in a hurry (i.e. in the boat when you've run out of leaders or need to re-tie your very last "hot" rig.