Yoshida is certainly one of the most talented musicians in the Japanese music scene now. Quite frankly, I'm not sure where you're getting the impression that Koenji Hyakkei is harder to listen to than Ruins. Koenji is like candy compared with most of Yoshida's projects, and perhaps even Boredoms. Koenji songs have structure and melodic flow. There are little gems hidden in them that you really have to listen a couple times to find.
Just out of curiosity, which Koenji and Ruins songs did you listen to?
And my nomination for best VK musician? Inoran. He wasn't the greatest guitarist ever, but his parts were subtle and full of feeling. Although not nearly as noticable as Sugizo, he was the epitome of VK as a musical genre. Without him, VK would just be a fashion genre.