Neon Genesis Evangelion is an OG in mecha animes. The anime focuses on the struggles of preventing the apocalypse by showing 14-year-olds battling Angels (titan-esque creatures that want to destroy humanity) in giant robots.
One Piece is an anime that outdoes itself. It is one of the longest animes ever, with over 900 episodes. This hilarious shōnen anime is iconic. The characters are complex and loveable; the story is broad, and the plot is ridiculous.