Here's some points....
1. Although cool, Fett in ROTJ was essentially beat by a blind man waving a stick, I'd assume Superman is quite a bit more formidable than a blind man with a stick.
2. If sufficient time is spent away from earth's yellow sun, superman becomes powerless and equal to a mortal man.
3. Unlike Batman, Boba has no idea about Superman's kryptonite weakness, therefore would be unlikely to use this to his advantage ( of course barring any outside help/information from informed parties)
4. The best thing Boba has fought was a jedi, which despite their cool powers, pale in comparison to Superman, who let's face it is stronger, faster, tougher, and in alot of cases smarter than your jedi.
5. Superman as opposed to Boba, can survive in space without life support, therefor all he woul dhave to do is open Slave 1 to open space, and problem solved.
Therefore the winner- Superman