What's the best way and products to use to maintain OTWB duty type leather holsters?

It seems everyone has an opinion and no matter what product you mention you can find people who say that using it is bad for the leather. I'm trying to prevent good leather from drying out, and preserve older leather items that have been neglected for decades from continuing to deteriorate.

Also I have been using saddle soap to remove older coatings of now oxidizing oils and finishes. It seems to do the job well enough but I'm left wondering if I'm still hurting the leather.

I always look to the manufacturer of leather goods for their recommendation.  For example, Milt Sparks recommends Angelus Lustre Cream, Fiebings Carnauba Creme or Renaissance Wax for use on their holsters, magazine pouches and gun belts.