There is none. I've had multiple park ski's, and none of them have been the "best"
Some are obviously better than others for my skiing style but there will never be a best ski, its just preference. Right now I have a pair of moment jibs, which are great for park and hitting bigger jumps and such because of their stiffer flex and traditional camber (and skinny waist, and I also have Hellbents which, are obviously better for deeper snow and crud witht heir wide footprint and rocker, but I will sstill use them in the park for sure just for a different feel, and they wont be "worse" than my park skis.
Like someone said before, this question is far too broad, its like saying which car is the best, its totally opinion. Charmander will tell you to get a diesel truck, and then the rest of NS will say get a subie, same thing.... its all opinion.
Based on the little knowledge I have of you, if you are looking for a new park ski I would probably suggest the bluehouse antics, they are a ridic good deal online right now and seem like they are very well constructed (I have not skied these, but I bet they are dope, BH makes good stuff) If you want something more all mountain but still want park ability without losing edge to edge performance look at something 90-100 underfoot, such as the Mr or chronic cryptonite, or any other ski in that category, there are a plethora. This is before we get into rocker/early rise and tip taper and all that jazz.
My suggestion to you, asses your skiing style (mostly rails and small jumps? Big jumps? Lots of glades? Pow?) and sound off in this thread, with that and your age, height, skiing ability, weight, and past skis that yo have ridden and liked, and people can make suggestions, none of which will be the best, but all of them will work great most likely.