good centerpiece?

Not a very good centerpiece imo but a nice enough plant that should do well for you. I would suggest a Red Thai Lily.
 
I agree, it's not really what one calls a centerpiece plant. It's used more for carpeting effects.
 
I use regular chain sword in my 10 and being that the 15 isn't much bigger it might work for you . I don't know if you have seen my tank so here is a pic.

IMG_0007.JPG
 
When I think centerpiece plant, I usually think either a Sword or Crypt - a large, singular plant that draws the eye. The reason I don't think a Pygmy Chain Sword work would well is it's small size and ability to send runners all over the place.

Fishshrod, that's a lovely tank.
 
AquariaCentral.com