I'm surprised by how popular Ariel seems to be; personally, I find it a narrow and exceedingly difficult to read font, and find that I have to squint to read it and so, as a consequence, I really dislike it. Actually, I suspect that part of the reason for its popularity lies in its location on the font selection alphabet - i.e. it starts with the letter "a".
My preferences for any sort of text are Garamond (a lovely, clean, elegant 18th century font), Arno (a modern but very classy font), and the standard classic Times New Roman, which may be boring but at least does not strain my eyes.