I’ve been known to wear both, and even at the same time, but I wear a Fanny Pack off to the side (hip).
I can't play guitar with a sporran (or belt buckle) in front.

Photobucket is down at the moment, but see the large leather Fanny Packs at: http://www.nstarleather.com/optimizer/product/617.html

Although horizontal, it has about the same carrying capacity as a Nightstalker sporran.