The Han Solo film would offer the most for fans of the original trilogy in terms of character familiarity. With Han Solo, you get Chewie, Lando, The Empire, the Falcon, Jabba, Boba....it's a near foregone conclusion this film is made and could easily segue to Episode 4. Han is the central character but we get lots of supporting characters out of this.

But aside from that, I have no interest in seeing a back story for any of the other OT characters i can think of unless its a dedicated Boba Fett movie which has Western written all over it. A badass who doesnt say much and kills/captures people.

Do I want to see Luke working moisture farming? Darth Vader killing Jedi? Princess Leia doing political stuff? The rise of Gran Mof Tarkin? 2 hours of Yoda waxing philosophical? Not much fun or adventure in any of this stuff.

Oh....Wedge. The one genre hollywood hasnt really exploited to the nth degree is aerial dogfight movies. Lucas based his space battle scenes on old war footage of dogfights. This could be like a sci fi Top Gun minus the homo erotic undertones.