I really like your #36 what I miss to consider it my "one" is a nicer font. the font you are using is too common... are you keeping your best for when you'll be in the top 5 phase? :)
if you want to explore some other way make the Z graphical: we need some spirit in the logo!
@74 is not bad, but it doent come out clean like. Your #47 is still the best, but to be sure to win you need to expand the concept of the Zed some more...