I think when comparing them, it is important to consider what world they are in.
if they are in DC world, the DC characters will win, but in Guyver world, Guyver will win.
so let me suggest that when making these comparisons, bring both characters out of their own world and pit them i the real world.
I'd also like to mention, I saw the man of steel movie and looking at that guy, I think guyver would have a strong chance. But then I don't really understand why that superman is not as strong as what some people have described him as.