Opinion on fonts?

[Nullifidian]

Hey,

I'm typing out my internship essay as we speak, and I wanted to know people's opinions on font usage.
I want the essay to look somewhat elegant but not boring. Although more importantly, I want my essay to be readable.
I have set a rule for myself to use sans serif font for headers and titles, and serif fonts for the actual content. I also don't want to use Times New Roman, since it's so widely used already.
Right now I'm using Garamond for the content, but it could be subject to changes if I'm convinced otherwise.

My question to you guys is, which font do you prefer for your content and why? And also which font size you prefer for reading a physical document.
People experienced in typography and such are a plus, but anyone's opinion is welcomed.