As of my last update in September 2021, here are ten anime series that were highly regarded and popular among viewers. Keep in mind that the popularity of anime can vary over time, so newer series might have gained popularity since then. Nevertheless, these are some classic and widely acclaimed anime that have stood the test of time:

1. “Fullmetal Alchemist: Brotherhood” – A gripping tale of two brothers, Edward and Alphonse Elric, as they seek the Philosopher’s Stone to restore their bodies after a failed alchemical experiment.
2. “Attack on Titan” – In a world besieged by giant humanoid creatures known as Titans, humanity fights for survival behind massive walls. The story follows Eren Yeager and his friends as they join the fight against the Titans.
3. “Death Note” – A psychological thriller about a high school student who gains possession of a mysterious notebook that can kill anyone whose name is written in it.
4. “Naruto” and “Naruto Shippuden” – The epic adventure of Naruto Uzumaki, a young ninja with dreams of becoming the strongest Hokage in his village.
5. “One Piece” – A long-running adventure series following Monkey D. Luffy and his crew as they search for the ultimate treasure, the One Piece, to become the Pirate King.
6. “My Hero Academia” – In a world where most people have superpowers, or “Quirks,” Izuku Midoriya aims to become the greatest hero despite not initially having a Quirk.
7. “Steins Gate” – A sci-fi thriller about a group of friends who accidentally discover time travel and the consequences that follow their experiments.
8. “Sword Art Online” – A virtual reality MMORPG becomes a deadly trap, and players must clear the game to escape. Kirito, one of the players, embarks on this perilous journey.
9. “Hunter x Hunter” – The story follows Gon Freecss as he becomes a Hunter, seeking adventure and searching for his missing father.
10. “Cowboy Bebop” – A classic space western following the bounty hunter crew of the Bebop as they chase criminals across the galaxy.

These anime series cover a wide range of genres and themes, and they have left a lasting impact on the anime community. Be sure to check them out if you haven’t already!