I normally like leather holsters, but with a light on it I would use kydex or something stiff like it. Reason is because you don't want pressure on the light, you want it coming out of and going into the holster evenly without friction and you don't want it shifting as you carry it, so I'd go with a stiff holster.
I had a local leather store that specializes in leather holster make one for my 1911 with a 3" barrel and it turned out awesome. It is located in Noblesville and is called Crazy Bear leather.