Either a REC RSLL or a Strubel u-18 would be my choice if you want a seat similar to the factory offering. If you want to step it up some a Strubel U -21 titanium seat is real nice.
For a cool look you can take an ALPS triangular reel seat ( AH-12M size) and fit it into the grip. Do a Google search for Alps Triangle real seat. They are available though Batson dealers.