I thought your leather boots felt better because they were tall boots. NO? I am confused. Were they just paddock boots made out of leather?
Tall boots can help a lot with your position because they bring such stablily to the ankle. The stiffness of them ends up supporting your lower leg in a way that any paddock boot, leather or synthetic, can do.
I have leather half chaps. I use Grand Prix. They are very expensive but hold up very well. I just have them restitched at the shoe shop if the stitching wears out. Have ahd them for years! I also have a pair of Ariat half chaps made from leather . These are stiffer and look more like a real tall boot when on. They feel really great, but are so tight that it's a struggle to get them on over my winter weight riding breeches.
So, I do recommned leather half chaps, and the Ariats that look like tall boots are really nice. They should last for years and years.