On a functional scale 1-10, 98% of machines are about 2. It doesn't make much sense to train on just a sagittal plain since the body moves in multiple directions. Make sense?
functional in bodybuilding = build muscle . and anything that you can use to put tensjion on your muscles will grow you.
some machines are good some machines are bad, some machines are bad for person X some machines are good for person Y
free weighjt, machines..use whatever you want. that being said iwould recommend combination of both as you dont have to limit yourself unless you workout in very poorly equipped gym.