I have owend both Van Alstine and Sim. Both are good, just a little different. In this case, it would depend on which one worked best in a given system. This would not be a situation where one "smokes" another.
I have heard/owned the W3 and W7. I liked the W3 better because it was warmer sounding. How about the W5.3 SE, is it warmer or is it like the newer trend towards more transparency and detail, which sounds great on well recorded material, but not so much on other recordings that a most of us own a lot of?