I've done a fair amount of research on this topic - unfortunately discussions on leather care products are like discussions on motor oil or politics. Take the following with a grain of salt, from my experience there will be many people that disagree with anything said concerning leather care.
Some things seem to be consistent though:
You have to consider what it is you are trying to do: Clean, Weatherproof or Condition the leather. Many products are intended for one or the other, products that claim to do all usually do a poor job of each.
Saddle Soap contains sodium hydroxide which overtime will harden, darken, and weaken the fibrous structure. It's also highly caustic. I personally don't use it on leather goods though I can see it's usefulness for rugged, hard-wearing, fullgrain items that see heavy use -- like saddles.
Mink Oil or Dubbin is often synthetic or made from processed pork fat - so choose your brand wisely. It does a great job of softening tough full grain leather and providing water resistance. The oil essentially clogs the pores of the leather which isn't great for shoes that you want to breathe. As you said it tends to use an oily residue. Some say and animal-fat product will break down the structure of the leather over time. It, like saddle soap, will also darken your leather significantly. I use it on my leather motorcycle gear and that is all.
Bees Wax products, like Sno Seal or Obenaufs LP, are also meant to condition and weatherize leather. They are thought to be less damaging to the structure of the leather than animal fat products. They will also clog the pores of the leather and darken the leather. I use Obenaufs LP on my leather winter boots - where they have been knicked, the product penetrates more deeply, leading to a splotchy finish. And not in a nice, patina-y way.
Lanolin or Carnuba based products, like Venetian Shoe Cream or Saphir Renovateur, are primarily meant to condition leather (though it is my understanding Saphir contains a small amount of mink oil as well). They will slightly weatherize the leather but it will not last. They will allow the leather to take a finish, however, so it's really the only option for dress shoes.
Many people (myself included) swear by a very thin layer of coconut oil as a conditioner. It can go rancid if you gloop it on, however, but you are just trying to replenish the leather's natural oils, not provide a new finish.
This all is fully up for dispute as it's not entirely a hard science. Many people have varying opinions.
Personally, I use Obenauf's Leather Oil on my Saddleback briefcases. Obenauf's Heavy Duty LP on my winter muck boots (Redwing Beckman's), and plain old coconut oil on my leather boots meant for fairer days (Wolverine 1000 miles). It's important to keep dirt and dust off of your leather goods, it acts as a desiccant, wicking the moisture out of the leather. I brush my (good) boots off (most) every time I take them off and then (sometimes) brush them if theyve been sitting a while collecting dust. Be as anal as you please. When they do need a good cleaning I use Obenauf's leather cleaner (not sure if it's available any more). I believe it is orange based and requires a conditioning directly after.
Anyways --- this is a very long winded yet brief overview of many discussions I've read on the internet - so take it all with a grain of salt. Many swear by saddle soap or mink oil alone and many try to keep their leather as glossy and pristine as possible. I fashion myself somewhere in the middle.
Hope this somewhat helps?
