It’s counterintuitive, but a well-designed font can have a lot of subtle variation between letters and still look consistent on the page. The converse of this principle is that a font with too much consistency can be numbing to read. Cambria is an example of this problem. It works well on screen, but on the printed page, it’s a skull-clutcher. Guardian Egyptian, Elena, and Skolar are similar to Cambria but avoid monotony. So are Charter and Source Serif Pro, which are available for free.