Number #3 for me, the background and the colors look ace! You need to work on the typography, especially of the top navigation bar. Your line height and font choice seem odd and make the header area seems bizarre.
I'd either try a smaller font all in caps, with a slightly larger line height. Or use a completely different, more suitable font and again increase the line height.
Another point is that it's very difficult to determine what this mystical login form does when you first hit the page. It's great having something that looks appealing but if you're unsure what you're signing up for it could be the downfall of the page. You've got to remember users are lazy, they won't always navigate to another page to read a large amount of text about what site they're about to give their details away to.