One of my favorites. A superhero who, at the start, wasn't exactly heroic by nature (much like Spider-Man, over at Marvel), but learned some hard lessons (much slower than Spider-Man!) and eventually grew into a hero.
As a fan of superheroes, I love the idea that this character was a fan who made himself a superhero to escape his humdrum life (and his various mistakes).
Through the Flight Ring (and force field belt), he's got a Legion tie built in, and through his working alongside people like Superman, he's got someone with miles of experience as a hero, who *is* innately heroic and noble (at least pre 52) and is quite capable of taking that Ring away if he didn't think that Booster was living up to the legacy he'd seized for himself.
He's almost a Marvel character, fully human, imperfect, feet of clay and all that, so much more relatable than someone distant like Batman or utterly removed from the possibility of human failing as Superman or Wonder Woman. He (and Ted!) feels like a working man's hero, under-appreciated, and working twice as hard to overcome their own flaws, in a world of airbrushed supermodels (despite Booster being more of an airbrushed supermodel than any of them, living or dying on his image!), and still encumbered by the occasional bit of bad judgment.
Not born to power, or handed anything, he's pretty much the self-made man of the superhero community. (Along with many others, like the Atom, who also both discovered the source of his powers, and, much more heroically, chose to use them selflessly!)
Also, I'm a sucker for a shiny metal costume. The post-Crisis relaunch of Captain Atom also totally sucked me in with the shiny metal look!