I've tried many different positions, and through that trial and error found myself the most comfortable at center. The longer tails give me the stability I want for landing jumps and keeping me on my feet. They also help give me more pop onto rails. I like the shorter tips for switch take offs on jumps. They allow my tricks to start spinning easier and help reduce any drag or catching that can happen.
I had to borrow some park skis for a day a few weeks ago that were mounted pretty far back. I hadn't been on some in a while, and reinforced why I like center. Sometimes I would find myself wheelieing on landings if my weight was a little back. I found myself losing pop on jumps because there isn't as much tail to really pressure and produce that spring.
I still think it is personal preference though. This is what I like. You just need to try different points and see what you feel the most comfortable on.