I think Bakshi's apadation is TRUER to the story but I prefer Jackson's, just because I think the characters appear so much more heroic in the his film. Their decisions are more impulsive and self-less. It makes the story feel more epic and powerful.
However, hat's off to Bakshi. Jackson seems to have knicked quite a few of his directorial decisions. ;D

Here's a link if you'd like to watch it: link

I haven't seen the Ralph Bakshi one yet... However, I say the Peter Jackson one, simply because it did hold quite true to the books and, once the extended versions had been released, even more parts were added in. Either way, though, I still prefer the books over them both.

I've seen the Ralph Bakshi one before....and I say that one because was closer to the books. I still prefer the movies though.