Seths are stiffest of the three, although quite soft compared to others in its category. A really great ski. Ive loved my 179s and 189s. 179s are great for everything. Stiff enough for some light charging and all mountain use, yet soft enough in the park. In fact quite good at park.
Arvs are kinda like a softer version of the Seth. More park, poppy, fun oriented ski. They still handle all mountain well and are super fun in park.
VCTs are like the equivalent of Jp vs. Jules. A backcountry jibber kind of ski I believe. Ive never tried them but Im sure theyre sweet.