Speaking just for myself, I find it a more compelling narrative structure to allow Space Opera to the be SETTING, with Big Stuff™ happening in the background ... but not in the foreground where the campaign characters are. It's much more interesting (to me, anyway) if the PC's are effectively "walk on roles" in a Space Opera that's already in progress, rather than being the central focus of that Space Opera. By keeping the PC's as "bit parts" in a larger tapestry, rather than featuring them (prominently) as the
Key To Everything™ you can basically have the best of both worlds.
The Space Opera stuff IS THERE ... and the PCs can get caught up in it ... but they aren't the central axis upon which the Space Opera turns. They can participate in the Space Opera and their actions may cause (unforseen) plot twists in how the Space Opera unfolds, but the PCs are not the Load Bearing Main Characters of that Space Opera. They just happen to show up in it from time to time (like running across the stage).
So from my perspective, the best option is a Hard Science foreground with a Space Opera backdrop setting that allows a Referee to move between both form as the campaign progresses and plays out.
Besides, doing that also permits the
Applied Phlebotinum outcome, courtesy of the hitherto "unknown to the Space Opera main characters" PC party, who act as
wildcards that randomly intersect with the Space Opera plot, rather than as central figures of the Space Opera storyline.
Being regular schmucks who get mixed up in larger events bigger than them is often times
way more interesting than being
The Chosen One(s)™ foretold by prophecy, destined to become the greatest of-

