the more expensive ones tend to have better quality bearings, spacer/dust covers made from harder alloy along with machining on the dust covers to make em look different , although don't take that as read some are just expensive, tbh most ns bb's are pretty much the same quality wise, go for the brand you like, personally i just buy the ones on sale (tight arse
)
currently using bb from
superstar, alone (Spanish) sunday, mankind, stolen, superstar, (mid) eastern,profile (us) demolition,odyssey(euro) no issues with any of em