i already watch bleach and naruto I haven't gotten into death note, but i have heard good things about it.
Currently, the battle for the title of "Most Popular Anime(MPA)" is striving between the 3 leading animes: Bleach, Naruto Shippuden, and One Piece. Personally, I prefer Bleach and Naruto Shippuden, for its better artistic rendering, surpassing One Piece's artwork. But, this is only of the current ongoing anime, Not a fight between the past and present. This question is far too broad to be answered correctly. For instance, the Dragon Ball series and Pokemon series are also quite hard to surpass, but not many people watch it anymore. Why? Well there is a possible reason. It could be that those old anime's are no longer fit to rival with the latest animes, with its technological advanced artwork and graphics. It could also be that animes such as Pokemon no longer satisfy the needs of today's Otaku population, for it is consider "childish" now. It could be that it is just plain old. In the end, there is no way that there could even be a "Most Popular Anime", because of the ongoing changes in Otaku tastes and never ending creation of new, more advance, more pleasing, more "pervy" animes that just seem to grab your attention and lure you to watch it more and more. There is popular anime, but no Most Popular Anime. The name is no object, the knowledge is the pathway and truth. The most popular anime in the 2,000nds is Naruto Shippuden