There is an endless debate about what makes the best leather conditioners and dressings. Many people swear by their "generations-old" secrets passed down to them. Let's clear up the confusion: First off, leather is tough by its very nature and performs in harsh environments, so determining what works best in the long-term is often hard to discern. Secondly, when the leather has delicate stitching - typically nylon - the stitching must be considered when choosing leather treatment. Lots of leather conditioners work great for short-term softening of leather, but cause long-term deterioration in the leather itself and especially in the stitching. Prime culprits are chemical-based compounds such as petroleum jelly and products termed "compounds." Most leather conditioners are actually cheap chemical compounds, and cheap synthetic versions of natural products should be avoided. Beware of leather glove manufacturers who sell their own "special formula" leather conditioner or dressing. Often, these cheap compounds are used to build-in obsolescence in their gloves and mittens. Not good.
Some natural oils, butters and compounds are pretty good, but beware of individual weaknesses compared to other natural products that could be substituted to eliminate the weakness. For example: Olive Oil. Olive oil is great for moisturizing animal skin (which is why humans use it on their skin) but there is a catch: it has a tendency to promote organic growth. It can go rancid. That's not a problem on human skin if you bathe regularly, but on leather that is rarely cleaned with soap, that may become a big problem. This example illustrates why a leather conditioner product should take into account both the long-term and short-term impact of the product's ingredients.
The most seemingly contradictory and confusing debate in the world of leather treatments relates to "Neatsfoot Oil," a substance made from boiling cow's hoofs that has been used for a very long time. Some say it's great, others say it deteriorates the leather and damages stitching. Reality: there are two highly distinct "Neatsfoot" products on the market: 100% natural Neatsfoot Oil made the old-fashioned way, and Neatsfoot Oil Compound, which is a synthetic compound. Those who argue that Neatsfoot Oil is great are probably using old-fashioned Neatsfoot Oil, and those who argue that it damages leather and stitching probably used Neatsfoot Oil Compound.
As a consumer, you need to assess two things: ONE- what you are using the leather conditioner for, and TWO- what is your budget? Compounds are cheap and work fine for leather products that you don't intend to use in the long-term or leather products that have less stitching and are thicker. All natural, non-chemical leather treatments are more expensive, which makes them ideal for expensive leather products and gloves with delicate stitching you want to last as long as possible -ski gloves.