New TeX engines compared: LuaTeX, ConTeXt and XeTeX

The two biggest differences I noticed when I tried XeTeX was 1) the pdf files were much smaller than from pdflatex, and 2) I couldn't use microtype [1] with XeTeX.

I stuck with pdflatex to use microtype (which is awesome), and use pdfsizeopt [2] to crush the size of my pdfs.

(More details: LuaTeX also makes small pdfs and might be the way to go, but I haven't tried it much. The size advantage over pdflatex depends on the fonts in use. There is apparently microtype support for XeTeX in the works.)

[1] ftp://tug.ctan.org/pub/tex-archive/macros/latex/contrib/microtype/microtype.pdf

[2] http://code.google.com/p/pdfsizeopt/ and my notes on it: http://homepages.inf.ed.ac.uk/imurray2/compnotes/latex.html#...

False presupposition in the title: Context is not a Tex engine, it is a format, either for Pdftex (Context Mk2) or Luatex (either Context Mk4 or Mk2).

I have used LaTex to write a few books. I usually use TexShop for OS X which uses XeTex so you get the unicode support, etc. Again, for the Mac, the Aquamacs version of Emacs has goot LaTex support built in, and is a good alternative to TexShop.

If anyone still needs convincing that these are superior to, say, Word: http://nitens.org/taraborelli/latex

http://www.kergis.com/en/kertex.html KerTeX is nice and small.

Not what I'd call 'New'---these have been around for a while and depending on you needs do quite well. I prefer XeTeX because as one of the answers said, 'fonts just work'.