Latin Modern is very similar to the default Computer Modern font. It is of excellent quality. This font bundle covers the usual requirements, such as having a serif, sans serif, typewriter, and symbol font. Load the fonts using the following command:

\usepackage{lmodern}

Latin Modern gives us the following appearance:

It is still similar to the one in our very first recipe.

The Kepler fonts are a complete and well-designed set of fonts in various shapes. There are upright and slanted Greek letters, bold math glyphs, old style numbers, and several weights from light to bold extended. Even slanted small caps are available. You can get the whole set using this command:

\usepackage{kpfonts}

The appearance of our sample changes to the following:

The typefaces harmonize well. They are not very heavy, for example, the typewriter code better matches the greyness of the normal text, since it doesn't look as heavy as it did in the previous sample.

Some fonts exist only as text fonts, math fonts, or in a specific shape. In such a case, it is a challenge to combine different fonts, both regarding taste and scaling. Here are some examples that work fine together:

\usepackage{libertine}
\usepackage[libertine,cmintegrals,cmbraces,vvarbb]{newtxmath}
\usepackage[scaled=0.95]{inconsolata}

Together they give us this appearance:

We loaded the Linux Libertine font. It is not as dense as a Times font, but denser than Computer Modern. Then, we added the newtxmath font, but programmed it to use Libertine glyphs when appropriate other than using the Computer Modern integral and braces symbols. The last option tells newtxmath to use another good blackboard font with \mathbb. Try this selection and check whether you like it, omit options to compare with the default settings. For details and further features, refer to the newtx manual via texdoc.

Finally, we loaded the excellent monospaced font Inconsolata for typewriter font-like shape, and scaled it a bit to better match our text font.

Now, let's try another combination:

\usepackage[sc,osf]{mathpazo}
\usepackage[T1,small,euler-digits]{eulervm}
\usepackage[scaled=0.86]{berasans}
\usepackage[scaled=0.84]{beramono}

You can see the difference, such as more upright shape for variables and integral and summation signs:

We loaded the mathpazo package, which gives us a Palatino text font. We replaced its Palatino Italic-like math font by the Euler Virtual Math font. It's basically the Euler font with missing symbols taken from Computer Modern, which is why it is called virtual.

In addition, we loaded the Bera sans serif font and the monospaced Bera shape for the typewriter text; both are appropriately scaled.

You may have noticed the options sc and osf for mathpazo, that is, for Palatino, which gives us a small caps font and uses old style figures as the default.

Now you have some good suggestions for a fine font selection. Using any of them, your document will look professionally designed and still different from a LaTeX standard document.