People prefer to go online to watch movies is because they get the benefit of watching HD movies online that is free of cost, fast streaming online and free download of new hollywood bollywood movies. One such site is Dudmovies
In their website they had categorized movies so that people can watch according to their taste i.e.. Science fiction, drama, comedy etc. Also they have the filter to show you movies at random which is like Google's "I'm feeling lucky" feature. Please go try and have a look