Actually, Darth Vader nearly ended up having his head blow off by Boba Fett. Darth Vader was out to kill Fett at the time, but Fett outmaneuvered Vader and had the chance of shooting Vader in the head, but it would have called all of the Empire down on Fett's head so Fett didn't take the shot.
Sorry but that fight was PIS
Plot Induced Stupidity
Meaning no matter what happened, Boba was gonna have to win/escape being that the fight took place before ESB/ROTJ so he had to have lived. If Boba didn't appear in ESB or rather he didn't appear in ROTJ, then Boba would have just been crushed. In fact, the reason Boba survived that fight was because of a box when again that doesn't make any sense because why wouldn't Vader just crush Boba and take the box anyway? So again...while that fight is canon(which it shouldn't be) its complete PIS in the favor for Boba.
Boba is like Batman, they both have PIS moments. Difference is, with Batman's PIS its usually not canon within the comics, with Boba that isn't the case when some of those PIS moments need to be N-canon. In an actual fight
Vader > Boba, every time.