I like picture 3..with an explanation. It is the only view were there is a very nice, subtle curve to the trunk line. After the thick protruding section on the left is removed, it opens up a beautiful informal upright trunk. At which point, you could let all the branches grow wild, then cut back to the ones that you need. Here are a few virts. The first one shows the pic I chose. The second, my proposed trunk line. The third is with the proper future branch placement and possible jin and shari.
If I may, I think a broom style on this tree would really lessen the quality and impact of this tree. In the end, you might just have somethign that looks like a bush. Cotoneasters, sometimes aren't the best for brooms. You have a beautiful strong, yet elegant curved trunk. Why not utilize that. Also, Since the leaves are so small, when this tree is near finished. I can picture beautiful foliage pads made up of very small leaves against a very powerful trunk.
Rob