This is the "it really depends on chemistry and passion" answer you were possibly dreading. It really does though! I'm a fan of teasing in a relationship, so I guess I'd be the teaser if the person was shy...I'm usually the teasee (hehehehe that's funny! THERE'S NO SQUIGGLY RED LINE! I AM A GRAMMAR GOD!).
Since I haven't been attracted to many people that are shy, I'd have to go with the latter of the two: Somebody that is always the center of attention. I do have a really big tendency to become jealous though...Ah well!