I believe that you are finding the same thing that I found when auditioning many different brands of modern, decent speakers a while ago - they were all 'similarly good' within their price point & class. They all sounded fine, although each had it's own sonic character; however, I could have lived with any of them.

I think your expectations of on-walls as contrasted to your full towers are a little high. The only way to level the playing field is to add a bunch of low end...

TAM