To clarify, my favorite was whichever one was the right fit for what I was cutting. Going bristle-free is desirable when you’re using a shorter endmill, like our 102 1/8". It doesn’t stick far enough out of the collet and would cause the standard bristle length to compress excessively, especially as your cut depth approaches 1/2". Bristle-less does not provide the best containment, but with a modest vacuum it is enough to more than neutralize the router downdraft, preventing smaller airborne particles from escaping. Bigger chips will still be flung outward, but they will settle quickly.