No real preference either. Space operas are fascinating, but I also happen to enjoy near-future stuff set on Earth, alternate history and similar scenarios. When it comes to reading novels, I constantly switch between the two without much thinking.
I guess it's a bit different with movies and TV. Cost-effectiveness often leads Earthbound stories to be set in the present day. And I often find the present to be quite boring (with a few exceptions like "Lost"), so space operas might have a slight edge here. But as long as Earthbound stories are not set in "our" familiar world (= the future, alternate realities, time travel etc.) I have no preference.
Most important to me are: Plot, characters, consistent world-building, sound science (unless it starts to resctrict the plot too much).