My choice was "stand alone, with different characters."
Why, you ask?
I don't have much time to devote to reading, so long, drawn-out stories, trilogies, &c don't serve me well. So, I'm not really part of the target audience. In fact, I can't even think of the last SF novel I read. Oh, wait! It was Dune! Last summer. It took me three tries over the course of a decade, but something finally clicked and on this last try I plowed right through it. Wonderful book. But like I said, other than being a Traveller fan, I'm not really in the target group. Most of what I read these days is 18thC history, specifically early colonial America with piratical and maritime leanings.