When writing stories, I find myself more comfortable doing so in Book Antiqua, 12, Dark Blue. It just feels more comfortable to read. I might change it though, because I write at 75% now, (at that zoom, I have two side-by-side pages and can read back as I progress) so the text is slightly smaller and Book Antiqua isn't exactly the best font for that, in retrospect... maybe Century Gothic will be better? Or even Trebuchet MS!
For University work, Arial, 12. I'm one of those stubborn people who sticks to the basics, rather than the defaults. Heh. That and we don't get reprimanded for using standard font styles.