I have a Bianchi Accumold holster that fits like a dream, but doesn't hold spares... Rip Off's, however, have multi pocket cases. Here's the pics of them on my duty belt:
As you can see, the Bianchi holster has a much cleaner look to it, with a nice, tight weave of ballistic nylon; it also holds it's shape well. It uses a belt loop, so once it's on, you pretty much keep it on. My light is an Inova XO3, with a strip of black reflective tape around the head. The Rip Off's case isn't as nice, but comes in a wide variety of shapes and sizes, and will allow you to hold your light and batteries together. Mine holds my trauma shears, sharp shuttle, and Gerber pliers. It uses a metal clip to attach to the belt, and won't come off on accident or while running. I love it for that reason! I can take it off of my belt if I decide to catch a nap between calls!
So, here's the rundown:
Bianchi
Pro's: Looks great, holds shape well, belt loop wide enough to accomodate most duty belts, uses two snap closures on flap to accomodate a slightly taller or shorter light.
Con's: More expensive, unable to take off of pants unless you take off your belt, should be "test fitted" with your light before buying
Rip Off's
Pro's: Cheaper, belt clip is removable
and secure, more types of lights/tools can be carried due to wide variety of sizes/styles.
Con's: Nylon fuzzes out a little easier due to weave, not as stiff nor protective as Bianchi case, uses velcro flap that can snag and fray.
*EDIT*-- I just found this on Doug's Flashlightreviews.com site; it's a holster for the Pelican M6, but if you can find one seperate on eBay, it may just do the trick! Beats carrying 123's in a Fenix holster...