These are my top 3 picks. These include Gundam series, Fullmetal Alchemist series, and Pokemon series. (These are my top 3 and i have a honourable mentions in the last so check it out)
#1 Gundam series The Gundam series has so many movies, shows, and figures showing giant mechas fighting for the control of the galaxy. Theres so many versions and series spanned from Gundam. Gundam inspired many anime in their robotic design known as "Mechs" Give this old historical anime a shot. You might love what you see.
#2 Fullmetal Alchemist series Why? This anime is a legend. With amazing music, the best openings and ending music, and story with characters, this anime is amazing. It got 2nd place due to having only 2 entries. But overall this is my favorite anime and this anime is worth the stop of 2nd place due to being the most well critically acclaimed anime.
#3 POKEMON! Due to the Pokemon series being a major influence in culture with it's vast shows, anime, video games, movies, card game, and more...this anime has truly been a staple on how anime can change the world. Bringing people together to Catch em All is a amazing experience.