I personally like the dead space of #4 but that's just me. My vote goes to #4 because even though #5 has a really cool photo on it. It just seems like a little to busy. To much busyness on it and you have to rotate it to see info.
Like with all photography it's a balance thing. I think number 5 SCREAMS K E E P M E !! Finding a reason for someone to keep your card is really the goal, nice image btw. My business card has 3 images on them along with all the other stuff and web site info.
I like the current font for #4 but the only thing I wonder about it is if there was less border or no border. I'm not sure if I'd be better or worse. Just something I wouldn't mind seeing a comparison of.