I've really gotten into park this year, so I'd have to say that. We don't really have any big hills around me, so I cant' really do the big mountain stuff. And urban seems sketchy to me.
Urban is kind of fun, but it takes so much work. I'd say clearly it's the most fun for me to watch, but those who haven't hit an urban rail have no idea.
I think part of the fun is setting it up with friends and having a good time, then hitting what you make. Even more fun if it's a really scary hit or rail.
For the love of god i swear nobody on ns knows the definition of big mountain skiing. To answer your question, yes big mountain is my favorite style of riding but it is probably not the "big mountain" you had in mind.