really, coke has very few advantages over gas.. so it really becomes a bit of personal preference, and the point has been argued for a while and by many.
anyway, with coke, its more traditional and you can get spot heating, and welding is fairly easy..(not coal.. coke)
and gas you can heat up alot of metal, no-low maitenance, easy, can weld, ect...
oh, and both fuels cost alot and polute more carbon than was put into them, or something like that..
charcoal on the other hand has a neutral or positive carbon emmision (which is good) if your eco minded, but more fuel is consumed, and its harder to get a hot hot heat compared to coke.