After much time and research I've come to this conclusion-
All of them.
I guess that is the theme this week (last post was "Taxes Blow")
From the treeless, aussie and endurance, to the standard english or western, to the new-fandango prototypes.... they are all and each inherently flawed in that they assume it is possible that any rigid structure cinched down on a horses back and made to carry 100-200 + pounds could possibly facilitate good movement, physical soundness or comfort.... and that any structure that isnt rigid could possibly distribute that poundage over more than just a few vertebrae.
We'll leave that argument for another time. I've tried my best to brush up on the very basics of saddle fitting and in doing so I found a tool that could be very handy indeed. It is a system created by Steele Saddle Trees (the trees are wood, the name is Steele:) called Fit to Be Seen. Steele makes saddle trees for many saddle makers from small custom outfitters to the big names like Big Horn, Simco, Crates, Reinsman, and Parelli, so there really aught to be a saddle (with a Steele tree) in most any price range. Most saddle fitter's I've listened to have insisted that there is no better way to fit a horse...or really there is no way to fit a horse BUT than to put that naked tree on his back and actually SEE where and how it is sitting. Even someone fairly new to saddle fitting would be able to fit their horse fairly well if they could actually see that tree... it doesn't take a rocket scientist to figure out something is wrong when there are big visible gaps or points sticking in to the horse. Many tack stores now carry a line of saddle trees for saddle fitting but carrying an inventory of trees is expensive, employing a saddle fitter to travel to barns is not always an option and having the horse come to the store can be inconvenient or just not feasible at all. So, what Steele has done is created a composite of the underside of the saddle tree that can be used just as you'd use a complete tree to saddle fit to the horse. The idea is that tack stores can carry a full line of these composites for their costumers to take out and try on their horses or a horseman can order a composite to try directly from Steele. Once you've found a Steele tree that fits your horse you can order a saddle or find a saddle with the correlating model number. It just makes sense!
Here is a link to read more about the Fit To Be Seen System
(FYI I have no affiliation with Steele:)