I grew up in the dawn of parks and freestyle skiing, I have rode with my share of pro riders and at one time was good enough to become a sponsored rider but I rode for the soul and didn't care about videos and magazines and such. We would build park features soon big then try to conquer them, my favorite was a 20 foot tall gap jump over the road and between the condos, so if you didn't hit it right and stay up you were in for some carnage.
Roundtop and Liberty are good because they are close, a place to get some turns but it gets old really quick as they are tiny mtns. The Parks there are not bad but very one faceted in features. Medium Table tops and step ups and a lot of rails. Roundup used to have 2 had pipes, one lil one and the biggest superpipe in the region which was awesome, but they got lame and removed all their half pipes, I lost interest and such when they did that cause I love boosting the pipe. Roundtrips parks are all built on beginner trails meaning very little gradient to the hill. I may be Biased but I lived and worked in Garrett County at the Wisp for years then moved back to eastern MD and started riding at roundup and liberty. I still remember the first time I rode Roundtop and thinking how tiny it was compared to Wisp, and Wisp is not that big. The half pipe was really what kept me sane there and I was pissed when they took it out to put a third lame rail park in its place. Roundup could make their parks better by adding and keeping different features like spines and 1/4 pipes, but every single park on the mountain will have the same kind of features, 2-3 big kickers then a bunch of rails and barrels, nothing off kilter (take off and land at an angle) everything is straight forward, and rutted out, sold hardback icy, and just boring, as I said earlier. For someone starting out it looks big and impressive, but until they see a real park, such as out west, they really are bound by their experiences. So in short I am not a fan at all of the RT/LB parks as they do not offer enough variety and are not steep enough to allow for true super kickers and larger features.
As for Wisp, since no one hear knows anything to tell you, It is bigger than the 3 local mtns and gets better snow due to location. The Parks there vary depending on who is building them. I personally loved the parks there when I was working the mtn. because they were huge, way bigger than anything you will find at the above resorts, the last year I worked we were launching off of about a 25 ft. tall kicker, over a table top, and if you didn't hit it balls to the wall you didn't survive well, haha. As for diversity, they usually have many different features, from the generic to the unique, big spines, small spines, 1/4 pipes, rails, boxes, etc. from my experience the park there is hands above Roundtop/libby. The hill gradient at the Wisp is massively more and that lends to being able to build and launch from massive features.
My favorite places to ride though are Timberline and Blue Knob. Both are big vertical MTNS, both have glade and boundary skiing, and Blue Knob especially has the only bowl in the mid atlantic. There is so much more to riding than parks and these two offer the best in the area for that. Plenty of natural features to boost off of.
I do like Blue Mtn. and is good if you can get there when the Jersey invasion is not there (as with most of the pocanos, not much for lodge aestethics but terrain is good). 7 springs is nice if there is a huge dump of pow and everything is covered, and the snow keeps the crowds from being able to get there (the top is flat and hard to get around and the crowds can be insane), Mtns south in Virginia are Tiny and often do not get much snow (wintergreen, massanutten, etc.),