For me, the answer to this question will always be One Piece, which I have referred to as "manga and anime's Lord of the Rings." I once wrote of it:
Oda has a talent for weaving disparate details together, collected from every cultural and historical source he can absorb, to create something new and exciting. This skill is most apparent in the colorful designs of his characters and the settings in which they are introduced. The One Piece world is populated by a veritable cast of snowflakes: hundreds of characters with unique visual designs, personalities, and origins, working as pirates, marines, government officials, privateers, revolutionaries, and more. In one part of the story, the Straw Hats fight to save a kingdom reminiscent of ancient Egypt from a sinister secret society. In another, they race enemies based on angels, native Americans, and the rapper Eminem (yes, really) to a legendary lost city of gold hidden on an island inspired by Jack and the Beanstalk.
I've found the main character's defiant optimism in the face of overwhelming circumstances to be encouraging and relatable during bad times and that's why I've always loved and connected to it so much.