If we're talking more generally about male voices, I like Kiyoteru.
But anyway, the kind of voice I'd love to see in an english male vocalsynth is one where it sounds clear, or powerful, in a regular high female range, while still sounding completely masculine.
Some examples of what I mean:
I can totally sing along to this! And that's the thing- when I write songs, I come up with the melody by singing to myself. But if I'm writing for a male voice, I ALWAYS have to completely change the key of the song. In fact, I'm going to be releasing a version of "insufficient" in the original key, because the currently released version with Kiyoteru just doesn't feel genuine to me. That, or change up the melody away from my original idea, or have to keep thinking about the range...
I want to write songs without changing what they're supposed to be, and I want them to be comfortably and naturally sung by male voices.