It depends on which one best describes you. They aren't synonyms; they are separate words with separate meanings.
Otaku: one who is devotedly obsessed with anime, manga, videogames, and related items. These things literally comprise a huge portion of that person's identity.
Weaboo: a non-Japanese who idealizes all aspects of Japanese culture and attempts to emulate.
Geek: an individual who has a high level of interest in a hobby or fandom that is not science or math oriented and has low mainstream appeal
Nerd: one whose primary interests are in the fields of science, mathematics, engineering, technology.
The only shared commonality is that all have a high level of interest in what they like and all the terms were created as derogatory names