Big Joker fan here.
Still, I acknowledge Ra's Al Guhl is right up there with the Joker when it comes to Batman's greatest foes.
My main sources of Ra's knowledge are Batman: Legacy and JLA: Tower of Babel. I collected damn near every Bat comic in the 90s and those were pretty much it.
Comixology had a Batman sale so I bought Birth of the Demon (which includes Birth, Son, and Bride of the Demon) and Death of the Maidens.
I also have a DC Universe subscription so I can reread Tower of Babel and Legacy. Also I'm pretty sure they have Resurrection.
Any other notable Ra's appearances I'm missing?
I noticed DC Universe has almost all of his earliest appearances, are those canon?
Anyway, just wanted to catch up on the Bat's (second) greatest villain.