OK, I can sum up my opinion of both pretty easily. Both were exercises in self indulgence and did nothing to improve on the original work. That anything failed to improve on the first is, quite frankly, an illustration of just what depths the director could fall to, as I didn't think that worse was possible.
That's fair. My own opinion is somewhat different, and since I opened the door...
JLA- Snyder's cut is better ... as in the whole movie makes more sense and has better character development. But it's also not a "director's cut" (it involved additional filming and a budget reported at $70 million, but rumored to be higher), and .... it's four hours long. That's not a movie that could have been released in a theater. So I don't think it counts as a director's cut, so much as a vanity project.
Blade Runner- This is a movie that has so many different cuts, that there's one collection with five different cuts ... and that doesn't have all of them. That said, if you do like Blade Runner (and I do, since it's one of the most influential movies in terms of the look and tone of "the future" to ever be released), I think that the usual points of contention are the Ford voiceover, the "happy ending," and the unicorn.
Personally, I like the version without the voiceover, but I also have seen people get very confused without it. As for happy endings? I dislike happy endings almost as much as bards.