Ghost wolf is 2 second cast with 30% movement increase.
Mount 100%/310% 1.5 second cast. Ghost wold is pretty useless unless in pvp situations, but it is still useless their cant even effectively kite really.
Both shaman dps specs routinely spec into Ancestral Swiftness, making it insta cast. Running around skinning Crocs in TB (or even better, places where you can't mount at all), insta cast GW >>>>> Crusader/ Mounts