Hi, have you decided yet? I have to admit that I’m a little biased here. I trail ride using my old dressage saddle. Western saddles tend to be more comfortable, especially for beginners, but eventually I got interested in dressage and switched. Now I wouldn’t go back to Western! I’m glad you plan to lease a horse before you buy–does that mean you’ll also take lessons? I think that would be a good idea. It would also enable you to experience both saddles, so you could make up your own mind. Based on what I’ve read, most veterinarians don’t like treeless saddles because they rest directly on the horse’s spine, which is why trees were invented in the first place: they rest on the muscles on either side of the spine, but never on the spine itself. With your attitude and desire to learn, I bet you’ll find the perfect horse for you and will enjoy a good long life together.