This is ultimately subjective and up to each person. I do not think it is the best anime of all time, but many fans do think this, and it is worthy of being in the top 10, for sure. The story is devastating, emotional, and able to teach the reader/viewer about themselves. The characters are quite good, too, especially in the case of the leads: Ed and Al. For me, the other cast members are a bit lackluster and uninteresting at times, but the series is always anchored by these two lovable protagonists, that are some of the best in anime history. It helps, too, that the writing is supplemented by a rich world and alchemy system along with great action. All of these components come together to make an amazing series that is one of the greatest anime and manga series ever created.