Again, thanks to all for some very helpful comments. I've been beginning to think that the British silhouette does not suit my body type particularly well (short with an 8+ inch drop). It was enlightening to take those pictures and line them up side by side. It's pretty easy to see how they contribute to a stout look. That said, I think they look better in motion than in that particular pose, but there is certainly room for improvement.
Jacket #1 is from Ravi. As mentioned, there is something funny on the shoulders probably due to a back balance issue as described by Chris Despos. I think this jacket is the least British of the four although it was supposed to be a copy of jacket #3. The front quarters do look weird because the material along the edge of the quarters tends to curl outward for some reason. One thing that I'm surprised no one mentioned is the positioning of the breast pocket. It's noticeably higher than on any other jacket I've seen. I don't think it should be quite that high. Lest I appear unreasonably critical of this jacket, I should point out that it fits me better than any RTW jacket I've had and it cost several times less than any of the other jackets pictured.
Jacket #2 is from Chan and to my eye is a very British silhouette with the roped shoulders, structured chest, waist suppression, and cupped skirt. I think that it fits well overall, but I'm less convinced that the overall silhouette is the best for me.
Jacket #3 is also from Chan but I included it because the shoulders have no roping and that has a dramatic effect on the overall silhouette. This was the first Chan jacket on which I asked for reduced shoulder padding and it came without roping, too. I'm fine with that, though, as I think it does look good. Ironically enough, jacket #2 was supposed to exactly the same as this jacket with the exception of roped shoulders and a slightly wider shoulder to correct some dimpling near the top of the sleevehead. As such, the significantly different look between jackets 2 and 3 can only be attributed to roped shoulders or the fabric selection since jacket 3 is a smooth worsted and jacket 2 is a textured fresco.
Jacket #4 is from Paul Stuart and is the only RTW jacket that I think comes close to fitting me. Along with jacket 2, I think it's the most British in its cut, too. It certainly has the most defined shoulder roping. Judging from all the comments, it may be the best-fitting RTW jacket I have, but it still doesn't fit that well. I can't say that I disagree, either.
At this point, I think I need to try a couple Italian silhouettes and see if they work better for me. This is a good example of why you shouldn't order five suits at once from a single tailor because your tastes will evolve and become more refined and you don't want to be stuck with a bunch of suits that reflect your less-refined tastes.