Wow there is some shitty advice in this thread. The OP asked for a BUTTERY fun playful ski that he wants to CENTER MOUNT. There are not a lot of skis that are designed for this.
EP Pros: I'm skiing on a pair right now until I can get some new bindings for my EHPs. Very soft, perfect to butter on, and symmetrical so they ski well center mounted. So much fun, so shitty at speed or in anything choppy, but any soft playful ski will be.
Hellbents: a lot like the EP pros, a little heavier (maybe I don;t know the weight but they felt heavier to me) and a little damper.
4FRNT YLEs: Haven't skied on but there design matches what your looking for and 4FRNT makes awesome skis. They're symmetrical and softer, which is what you should be looking for. I especially like their lack of sidecut, unlike JJ's, Opuses, and chetlers. [sub 20 meter side cut is not an advantage in pure pow, but is a compromise to make the ski feel better on groomers (because most people who buy pow boards don;t actually ski all that much untracked powder). These skis have a lot of taper to compromise for the loss of smearing ability caused by the extreme sidecut.]
4FRNT CRJs: Not fully symmetrical but pretty close. I personally thought they skied kind of strangely but some people like them a lot.
Skis to avoid if you are sure what you want. These skis will be a lot more versatile than the above skis, meaning they will hold up in crud and on groomers. DO NOT MOUNT THESE SKIS CENTER. Don't do it.
Bent chetlers: a little too stiff and damp to be super buttery, but over all the best "charger" ski of this group, but still really fun. I've only skied the 192s though.
Opuses: Light, playful, and not at all damp but IMO a little too stiff and cambered to compete with the first group of skis in terms of buttering ability. Again I've only skied the longest length so the shorter versions may be better in the playful buttery department. Super fun in the air but shouldn't be mounted true center.
JJ's: Light and "stiff", more directional, don't butter very well unless you consider rolling up onto the rocker buttering.
ON3P's: a little to stiff for what your looking for except for maybe the pillowfights but I haven't skied them.
Fuck proof reading I'm too drunk for this shit. Good luck with your ski search and happy new years.