Not trying to be mean or anything, just want to give my opinion on these:
One more Ridley Scott prequel: Voted Yes, it's hard to just let it end like this, besides all those Gigeresque temples and stuff are neat, just the Alien needs to look better and not a CGI'd POS. Has to have a great story though to work well. No dumbo mistakes either, like removing your helmet as soon as you land on a new planet, yes the oxygen levels could be the same but ever hear of viruses etc Ridley Scott? (2 straight movies you did this crap, what's up with that bat shit?)
Alien vs. Predator 3: Sure, why not, as long as it's not on Earth ever again, really dumb.
Blomkamp's retconned pseudo-sequel with Ripley and Hicks: After seeing this guy's 40 armed and legged Aliens, no thanks. Paul W.S. Anderson #2.
Sequel to Alien Resurrection with Ripley 8: With Ripley 8, no thanks, unless it's not on Earth.
Reboot the whole series and start from scratch: A STUPID IDEA! REBOOTS ARE STUPID!
Soft reboot, set within existing continuity but new characters: NO, NO, NO, NO, NO REBOOTS! REMAIN THE COURSE, look at what has happened to every damn reboot, reboots are dumb and lazy.
How about a movie with Amanda Ripley? Or just keep making movies with new actors, storylines and circumstances, such as in the comics.