>>3238671OP here: depends on which iteration of Devilman you want to start with, though starting with the original manga is probably the best idea.
Devilman Crybaby is the only full adaptation of the manga and does deviate in a lot of spots, but generally gets ratings of 8/10 from critics. It's my personal favorite out of all of them, and I recommend it.
Devilman The Birth/Devilman Demon Bird are really only worth it for the absolutely hilarious dub, though the animation is pretty nice in a lot of spots too.
There's also Amon the Apocalypse, but that one is basically loosely based off a published fanfiction and doesn't really give you much that Crybaby can't provide.
