I like Stylebot more. It integrates into the webpage better, so you can have live previews, and right click on an element to style in [0], and for basic changes

I like Stylebot more. It integrates into the webpage better, so you can have live previews, and right click on an element to style in [0], and for basic changes (such as hiding elements) you can avoid touching CSS at all. [0] Of course, it just takes its best guess as to which possible selector you really want to style when you do it this way.