So i've put in an episode of Firefly ("Shindig" to be exact) and was struck again how much in tone Firefly was when compared to Han Solo and his pre-Star Wars life.
For me Firefly was always a spritual successor to Han Solo and his adventures because of its similarities. The main characters share many traits.. both Solo and Reynolds are rogues who, at their core, are the most kind and caring people as evident in their protectiveness of their crew yet possess their own moral code which "allows" them to kill bad guys and take on illegal jobs to survive.
Both are hotheads leaping into action without thinking but through sheer determination, skill and often enough luck always make it through with minor scrapes.
They both possess old and worn ships of which they are hugely fond of and have tinkered with them (the Millenium Falcon more so than Serenity but that's not the point).
And both of them would die for their crew and friends and would do anything to keep them safe, they have both the same sense of humor and honor amongst thieves and they are both highly skilled and talented when it comes to the skills of the trade.
Additionally i see so many similarities between Nathan Fillion and (then) Harrison Ford.. their acting styles are similar and they both convey the playfulness and at times seriousness of their characters so well that i believe should there ever be a Han Solo live series it should be Fillion who plays Solo.