"Whether it will be released as an almost four-hour director’s cut or split into six "chapters" has yet to be decided, but the Snyders are now in the midst of reassembling much of their original postproduction crew to score, cut, add new and finish old visual effects, and, yes, maybe bring back many of the actors to record additional dialogue." -this link

I think the limited series way is probably more likely. They're reportedly spending $20-30 million on post-production. If they release it week-by-week, that's 6 weeks. A typical streaming subscription goes by the month. Meaning if you wanted to watch each one as it came out, you'd have to pay for 2 months, rather than just the one if it's released in one big movie.

But personally, I don't really care about the format. I just want as much of it as I can get. XD