For those who want to easily control the layout of their pages (i.e. where widgets go, the position of navigation menus, where the header appears, etc.), the iThemes “Builder” framework is hard to beat. It gives you an enormous amount of control. You also have easy control over fonts, borders, and colors.
That said, apart from a few exceptions, the out-of-the-box themes seem relatively plain. Some seem somewhat dated. Out of the 180 themes advertised, I found a (growing) list of 33 that were responsive; however, at least more than 10 in that list were different colored versions of another theme.