I don't care about the 100% / completionist kind of thing; the collectibles are fun as an integrated part of the exploration--always looking out for them, getting into some interesting puzzles as a consequence--but I don't see the appeal of going back and trying to check them all off a list.
Anyhow, all 3 of the main games are absolutely incredible in how well they nail the perfect Batman world. It's like the Animated Series mixed with a bit more of the comic book, and that makes it far better than any Batman theater experience (as popular as the Christian Bale movies are, I would argue that Bale's Batman barely even deserves mention compared to Kevin Conroy. Conrary is Batman, Bale is some weird knock-off imitation even at his best moments).
I tried Origins and dropped it less than 3 hours in. I just hated the style of everything, the introduction to the story, etc. I guess I could try again but I found everything irritating.