For a western saddle, I use an Arabian tree Circle Y. For English, I use a Bates.
For me, the problem is that the front has too large a horizonatal gap.
When people talk about a wide saddle, they usually mean the ANGLE of the bars in front, with wide = larger angle. Imagine an upside down V. As the distance between the points grows, the angle becomes wider. Now draw a horizontal line near the spot where the V joins. As that horizontal line gets longer, the GAP grows wider.
I need a wide angle, but a narrow gap. If the gap is too wide, the saddle comes down too far on the withers. In an ideal world, we all would have custom saddles for each horse. In the world where I live, I've taken to using this: Fleece Western Wider Wither Pad - Statelinetack.com
For $8, it fills in the gap and keeps the saddle off of his withers. It also tapers gradually in thickness near the edge, and I have yet to see any signs of a line or any irritation where it ends under the saddle. I don't need it for the western saddle, but it works great with my English/Australian saddles.
And at the price, if it doesn't work, you can toss it out without feeling guilty.