check http://www.linux.org/dist/index.html , you can search for category of use, plattaform, language, etc
but my two cents go to
gentoo linux http://www.gentoo.org/ (yes, the source based one!) the best if you want to play and learn linux!
have fun!
another good site for choices in a *old* post by
felixml: http://distrowatch.com/