Prior to The Force Awakens, if you wanted good, seemingly classic Star Wars stories the best place to turn was Bioware's Knights of the Old Republic. In many ways it still is, as the MMO follow-up The Old Republic may have lost its prefix, but none of its grand storytelling. Set thousands of years before A New Hope, it'd be pretty easy to incorporate most of that game -- and its accompanying sequels -- into the new continuity. Ancient history can't really bite Kylo Ren and Rey's style if it happened millennia before they were born, now can it?
But if you had to pluck just one character's adventures from that era Darth Revan seems like the obvious choice.
Like Mara Jade, Revan is a Star Wars polymath: fighting for the light, the dark, an empire, and a republic. They caught one of the best supporting casts in EU history in their gravitational pull, and carried with them on memorable adventures that establish hundreds of years of Star Wars history. Not to mention that Revan's trademark mask was clearly the inspiration for the aforementioned fashion of Kylo Ren.
To make mention of Revan and The Old Republic -- even as apocryphal legends -- in the new continuity would be a guaranteed hit with fans that sought out bright spots during Star Wars' oh so very dark years. It would also intrinsically add a mountain of progressive representation and characters to its back story. While Disney-approved comics and novels have already established queer relationships in the new continuity Bioware was doing it more than a decade ago.
Revan might not be the absolute best solo character to come out of Knights of the Old Republic (that position if of course filled by HK-47, meatbag) they represent a whole lot of history that seems worth reworking into the fictional textbooks.
And hey, if someone wants to throw HK-47 in there too, I don't think anybody will complain.