Ok, so a park specific ski would be good.
If you're not really that good, and don't want to look like to much of a poser, The Salomon 1080 Thruster is a good one to start on. Durable too. (I've had a pair for 4 years)
(don't get Salomon bindings though!)
Scratch FS rides a lot like the 1080, it's a light ski so it's easy to butter and spin fast.
Dynastar Trouble Makers I hear are really fun to jump with, but are supposidly really bad for rails.
I wouldn't know about Armada or Line, someone else might want to help there.