When I started to know about TEX, I found it a descrptive language. I think that any XML based alternative would do the job better. And everybody would not have the hassle of learning TEX. I found it quite time consuming. Does anyone know any XML based alternative like this? And if there is compatibility between that thing and XML (having same elements or one can be converted to another) theb that would be nice.
I think you're probably barking up the wrong tree, but there is Prince, an XML + CSS to PDF rendering engine.
I suppose the closest thing I can think of is Docbook. It's a pretty flexible markup language for producing technical documentation, from man pages, to articles, to books.
Still, though, I think TeX is the better choice. More power, more tools and just prettier output. If you want to produce very nice-looking documents with TeX/LaTeX but without learning much about either, I suggest you look into LyX, a nice graphical editor that allows you to create documents more or less like you do in a word processor, but with much nicer results and access to the full power of LaTeX (albeit sometimes by embedding LaTeX commands in your LyX document).
I'm assuming here that your goal is to manually create documents. If you're looking to generate them automatically from something else, Docbook might be a better choice.