B89 for...really quite a few reasons.
Firstly, that was the movie that got me hooked on Batman, that's the movie I watched more than anything else as a child, etc., etc., so that automatically gives it a bit of a leg up.
But beyond that, I also felt it was a lot closer to - not exactly the comics - but the feel of Batman (as ashtonu mentioned - it did really feel a lot like DKR).
I preferred the art direction and the original vision for Gotham a lot more than Returns, and it also wasn't as dark, as, simply put, freaky as Returns. Returns is a good movie to be sure - I enjoy it - but it does get pretty weird at times, whereas B89 isn't tarnished by that...weirdness.