Mollard, I'm glad you decided to repost your question. Since no one has chimed in yet, I'll attempt an answer.
First, it's important to keep in mind that leather is a natural material that will break down over time -- regardless of how well you protect and take care of it. There are certainly many products on the market that can extend the life of leather, but you'll find there's no definitive "best product" out there. I personally use Satin Shene, an acrylic topcoat, on my items mainly because it plays well with Eco-Flo dyes and provides a measure of water resistance. There are others who will swear by other products, like Montana Pitch Blend, Picard's, etc.
I'd very highly recommend purchasing small quantities of each and trying them out to see which one works best for you. You can apply them to leather samples, and then expose them to the elements, etc. I know that many here on this forum rarely build items for themselves, but I believe it's good to carry and use the stuff you make on a daily basis. That way, you can see first-hand how it functions and wears over time.
I know this isn't the answer you were looking for, but I hope you're able to use this information to help make an educated decision on leather finishes.
Regards, -Alex