I'm not deep into Swanö's work, really only knowing him from Star One. I tried one of his solo albums once, and totally dug the music, but couldn't get into his own vocal delivery. Kürsch has a very distinctive sound, but Blind Guardian is one power band I just never latched on to. I have quite a few of their albums, but something just doesn't click.
Still, if I had to just have one, I like Hansi's voice better.