My humble fonts recommendations

All fonts listed here contain polish characters. The fonts are available as TrueType (TTF) or OpenType (OTF) fonts. How to use them in LaTeX? See my XeTeX and LuaTeX page.

Serif fonts

Garamond
Standard TeX font (ugm) but available also in OTF format. Very elegant, maybe too much for everyday use.
Cardo
Very nice, elegant, general purpose font. The main drawback of it is the italic style which is slightly too condensed.
Linux Libertine
Currently my favorite. Elegant and plain with good italics. Almost as good as Birka, slightly wider.
Junicode
Elegant, with nice italics, maybe slightly too small by default. More ornamental than Linux Libertine but less than Garamond.
Sorts Mill Goudy
Interesting and stylish font but lacking bold style and with slightly strange floating italics.
Habibi
Like Sorts Mill Goudy: interesting and stylish but lacking bolds and italics. Requires some scaling down.
Gentium Basic
Nice and with a character. Unfortunately lacks two polish letters: ą and ę :-(
Alegreya
Interesting, rounded with strong serifs. Works reasonably well in math mode.
Neuton
Rounded, with condensed italics. Similar to Alegreya but heavier. Does not work well in math mode. Has 5 different weights: Extra Light, Light, Regular, Bold, Extra Bold.
Noticia Text
Tall, dense and boxy with slant italics.
Cambria
Quite pronounced and heavy font. Somehow similar to Noticia Text. The main advantage of this font is availability of matching glyphs for math mode called Cambria Math (use unicode-math package). See Consolas below for availability.
Minion Pro
Adobe font distributed inside Adobe Reader Font Packs – extended languages (Win, Unix). It is also available for standard TeX.
Birka
Very very nice commercial serif font used by default by O’Reilly. It is lighter than Linux Libertine or Minion Pro and has the same width as Minion Pro.
Bergamo Std
Similar to Birka but heavier. However, there no polish glyphs and italics are too condensed for me.

Sans-serif fonts

Open Sans
Very similar to Trebuchet but lighter and more sans, just plain. There is also Open Sans Condensed version.
Lucida Grande
Similar to Lucida Sans. Used in Max OS X user interface.
TeX Gyre Adventor
Stylish. It is a replacement of classic Avant Garde font.
Ubuntu
Quite rounded and plain. There is also Ubuntu Light version which is slightly bolder then Open Sans Light.
Trebuchet
Classic but with a style. Freely available at Microsoft typography.
Calibri
Similar to Ubuntu but lighter (Ubuntu Light is still lighter). See Consolas below for availability.
Sansation
Modern and wider with a smell of Verdana.
Myriad Pro
Another Adobe font distributed inside Adobe Reader Font Packs – extended languages.
Franklin Gothic Std Condensed

Monospace fonts

DejaVu Sans Mono
Nice, slightly narrow, rounded font almost identical to Bera Mono available for TeX.
Lekton
More technical then DejaVu Sans Mono, and lighter. Produces nice contrast between regular and bold styles – usefull for code highlighting. Does not contain ASCI art box glyphs and the “^” character.
Consolas
This font, along with Calibri, Cambria, Candara, Constantia and Corbel, is distributed with the free Powerpoint 2007 Viewer and the Microsoft Office Compatibility Pack. There is also an open font inspired by Consolas: Inconsolata. However, it does not contain bold and italic styles.

Math fonts

Cambria Math
Smooth, delicate, slightly condensed.
Asana Math
Quite light, wider than Cambria, elegant.
XITS Math
Quite pronounced, accented symbols, wider than Asana.