It really depends on what kind of ski you like, both are legit companies. It's better to choose a specific ski to ask about though, not a whole company.
more like:
seth morrison, sean pettit, pep fujas, andy mahre, pk hunder, michelle parker, sean jordan, charley ager
or
kye petersen, kevin rolland, xavier bertoni
All the park skis are redesigned and brand new for this next year. New shapes, new top tooling to eliminate chipping and reduce weight and all new camber profiles.
I usually never even think of K2s when it comes to park skis (powder and all-mountain is a whole different story, they're one of the tops on the list for those categories), but I'm kinda itching to try out these new designs and might pick up a pair of Domains or Revivals when my shop gets them next month just to try them out.
i'd say rossi. my k2s snapped and any rossi ski will be lighter than the k2 equivalent. but unless you're getting them for really cheap, i'd get a different brand.
Rossignol- S4=best park ski ever made K2- Kung Fujas= allmountain killerRossignol- S7= OMG WANT K2- Pontoon= Floats real good and stuffRossignol- S5= All Mountain jib stick looks real sick shreds park tooK2- Rivival= looks really fun rockered park ski Rossignol- My choice