Given this question a significant amount of thought, and am plumping for Alan Dean Foster's "Commonweath" novels. Not because they are great literature, but because they are and alternative to Star Wars and Star Trek that is neither grimdark nor hyper-serious. And most importantly, doesn't have a cult following of rabid fans who will object to anything that is remotely different to the novels.
Or you could do the same with Poul Anderson's Technic setting.
Another idea would be Larry Niven's Ringworld. But a very loose adaptation, focusing on the survivors' adventures trying to cross a very very large world with a myriad of different cultures. An episodic structure that would be well suited to steaming TV.