It's all about the story really, I liked that Watchmen was a really high quality 9 episode banger - one and done.
I also like bigger story's, but I'm not sure the material would warrant more than two seasons if its a linked story. I'd imagine it would turn into some kind of Weyland Yutani wicked corporation drama and the Alien would just be background noise to Burk esk baddies running around and android reveals.