Ariel style seems the most useful when going for the mount. But, again, insect glaive user so for me that's pointless. It makes the vault more out instead of up. As it is I'm used to it going more up then out, so it would just be bizarre and take a while for me to get used to. Perhaps I shall...
I'm an insect glaive user, so I have no need for their ariel style and I don't like the looks of the adept style. I have yet to see the other style, since Guild is what everyone's used to.