I really like this one (#3). It's very different from the other submissions, and I like it more each time I look at it. I don't even really have any constructive comments. If you have any other ideas, please feel free to submit them. This logo (#3) will get some serious consideration.
After looking at #4 some more, I would be interested in seeing what it looks like with a slightly sharper font and maybe a slight curve on the bottom edge of the line, if you have a chance. Thanks!