These two are kind of bland. I only like the one you have in your sig. Although, I do love the text for them. Also, try sharpening up your renders and the backgrounds and don't make your sig over 400 pixels. If you did, then you would have a lot of empty space to fill. Try 400x125 pixels next time. Also, try to make the colors for your render and the color of your background match, if you can. Anyway, next time, try to look at some tuts.
Truth be told, I don't like the first one. The second one is all right, but I don't like how you blurred them. Blurring isn't the best technique. Also, the first one doesn't have alot of effects. Work on that.
