Any holster will cause wear on a gun over time but some are more gentle then others. Leather is typically thought of to be the kindest to a guns finish as it is soft. The Fobus you mentioned is kydex which is basically a hard plasitic molded to fit a given gun. The plastic will cause wear more quickly and in a different fashion then leather.
Leather will mold to the gun as it breaks in and you'll see the most wear around higher pressure points. Kydex wears more from drawing and reholstering the weapon, where ever it makes contact during that process.
I carry a Crossbreed Supertuck which a hybrid. It's a leather back with a kydex mold attached to it. I absolutely love it, can wear it anywhere even while driving and I can still tuck my shirt in. Check them out.
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"Best" is hard to define. Best really depends on you and what you want out of your holster. A plastic holster (you can use different words but plastic they are) is faster (unless you are using one with retention). Fobus holster are more than serviceable and usually run less than $25. Quality leather holsters usually will start at twice that, and sometimes much more than that. I seem to have better luck concealing a leather holster, it's "lines" seem to blend better to my body. I have also found that poly guns and plastic holsters work well together as the two materials don't seem to wear on each other like a plastic holster on a steel gun.
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I like and think leather best. But I am an old fashioned "put my magnum in a Bianchi" guy and don't mind a little holster wear on the barrel. It is minimal anyway. It just gets that way after a few years of use/carry. It just gives the magnum a little character.