I'd recommend 'One Piece'. It has a wide range of characters and an engaging story that's easy to get into.
Try 'Attack on Titan'. It has a unique premise and intense action that can draw you in right away. The art style is great too and it's gained a lot of popularity for a reason.
You could start with 'Spider-Man'. The classic superhero story has simple yet exciting plots and is quite accessible. It also has a rich universe that can keep you engaged for a long time.