legit (in order of prestige and importance to my understanding in the heavy division):
IBF (because of what holmes did back in the 80's)
WBA (Originated during the ali era and was once held by him)
WBC (a few people think that this is the last legit belt due to the wbo's recent debacles)
WBO (End of the line as far as legit belts go. due to its recent champions and fights this belt is almost laughable)

the 4 other belts that are just legit enough for you to be considered in a conversation about something realted to boxing (i'll try to make this in order as well but in any case the wbf is the worst):
IBO (its been held by some respectable fighters)
IBC
IBA
WBF (Just look at the letter combination, it doesn't even look important regardless of what the letters stand for)