I use a loop knot on everything but dry flies. any fly you want to have some action or to be swung needs to have full movement in the water and a loop knot allows it to be free to move. using Clinch knots will work of course but you will notice your fly has more freedom when tied with a loop.
love the loop, it will love you back
I mainly don't use loop for dries because I think the loop dragging in the surface film will cause the fly to partially sink, have strange action, track incorrectly.......etc
Chehalis - thanks for the C Neil suggestion. not sure why I never thought to use those for pinks LoL