Option 3, as presented by Qworg, seems like it could be a lot of fun provided that it was indeed something somewhat less common, as Radar suggests; the occasional derelict ship orbiting a planet or a star in an out of the way system might add some gameplay for some players who like not only creating a space for themselves in the universe, but also exploring and discovering what the world has to offer. If excluded from the core, though, I think it would certainly be ripe territory for modding support.
Comparing the other options, I feel as if option 1 is somewhat limited and, to me, lacks a certain sense of identity and a story direction. Certainly, we would have the DCPU and a general "hardcore" atmosphere, but with what goal? What drives players forward? Exploration of an empty universe only goes so far, in my opinon.
However, options 4-6 may provide too much stimulation and too little options to actually explore and make your way. Option 4 is perhaps the least intrusive option of the bunch, allowing for the range of non-spacefaring races to range from basic organisms (ie. Animals) to scattered tribes to interact with and finally to real civilizations. I think the more complex creatures you come across in the universe, the fewer options a player will have to make of it as they will.
Anyway, I am an advocate of option 3 (perhaps implemented in a mod, though I think it creates some drive to explore and discover more of the universe) while perhaps expanding what players will encounter to include basic animals (to create threats to players on some worlds or simply to add color to the universe) and possibly to basic tribes (some that may be hostile to players and others that may be more hospitable).