Looking at just Medico briefly, they apparently came in briar from 1933 to 1966, then either briar or a synthetic called Brylon, are made by S. M. Frank, which I've heard of, and they apparently pioneered and patented amongst the first ever filtered pipes.
Vintage 1962 Medico ad. I love stuff like this.
Will use the site for info on the other 2 brands. Thanks for your info