<p><pre><code> body {
font-family: sans-serif;
font-size: 16pt;
line-height: 1.6;
}
h1, h2, h3, h4, h5, h6 {
font-family: serif;
}
</code></pre>
That's readable, thus a minimum standard for beauty.<p>Use of colour, spacing, case, image then become important for making powerful prioritisation, focus, structuring absorption/presentation of your message. A specific font may or may not be part of this, and advantage of system fonts is not just their speed, but their familiarity - this can also be a disadvantage if intentionally seeking to disjoint a user or place them in a context associated with the font.