How closely does the One Piece manga align with the anime?

It follows pretty closely. There are only a few minor differences that don't really change the main plot or characters' development.

The Haikyuu anime is pretty consistent with the manga. It replicates the characters' development and the major events accurately. Minor adjustments here and there are mainly to make it more suitable for the anime format.

It does to a large extent. The anime mostly adheres to the manga plot, with only a few minor differences.

The Attack on Titan anime is relatively true to the manga. It keeps the main plot and character developments intact. However, there are minor alterations made to make it more suitable for the animated format, and these changes don't significantly deviate from the manga's essence.

It's quite close. The One Piece anime mostly adheres to the manga, with only a few minor differences that don't significantly impact the main plot or characters.

It follows quite closely. The anime mostly sticks to the main plot and character developments from the manga.

It's quite close. The anime mostly adheres to the manga plot, with only a few minor differences that don't change the core story.

It's reasonably close. The anime mostly adheres to the manga plot, with a few tweaks here and there that don't significantly change the main story or character developments.

It's reasonably close. The One Piece anime mostly adheres to the manga plot, with some filler episodes for added entertainment.

Overall, the One Piece anime does a decent job of adhering to the manga. Some arcs might have minor differences in pacing or animation style, but the core story remains intact. Also, they sometimes expand on certain scenes to add more depth.