Thundering Sierra gets my vote.

I vote Thundering Sierra. The CSO terraforming skills are staggeringly more complex than anything that we've seen here before for RCT2. That is to say, if anyone has even done CSO terraforming in the past before, which I find hard to believe.

I voted for Nexus; I found Screamin' Demon to be very generic, with no scenery additions to make it pop.

If only I could build like that in RCT3

Believe it or not that is how i started. It took about 2 years to get really good.