How closely does FX's Legion follow the comics?

Not really. There are quite a few differences between Legion and the comics. Some characters and storylines have been significantly altered.

It follows quite closely. There are some differences, but the main plot and character developments are similar.

It follows quite closely. The main plot and key characters are consistent, with only a few minor tweaks for the medium of TV.

It varies. Some aspects are very close, but there are also changes made for the cinematic adaptation to appeal to a wider audience.

It varies. Some storylines are very similar, but there are also significant differences to make it more suitable for TV.

It varies. Some aspects are quite similar, but there are also notable differences to make it more suitable for the TV format.

It follows quite closely. There are only a few minor differences that don't change the main plot.

Gotham has some elements from the comics, but it also takes creative liberties. Some storylines and characters are adapted differently.

Endgame takes inspiration from the comics but makes significant changes to fit the cinematic universe and storytelling needs. Some characters' arcs and events are quite distinct from the comic counterparts.

It varies. Some MCU movies and shows stick quite closely to the comics, while others take more creative liberties and make significant changes.