While most of these lists are arbitrary, most of the people in this thread don't get the point of the thread. The anime in my list (>>11743229
) are anime that people constantly have flamewars over, or at least used to. You cannot participate in the majority of /a/ discussions without having seen these anime.
I didn't include current shit like Code Geass or even Lucky Star and Gurren Lagann because they are so recent and they are very likely to pass into obscurity in the next couple of years. The anime in my list have passed the test of time and people still constantly - or at least used to - bring them up, long after the series ended.