Despite what most people above say, I most often see bitstamp as the price of reference in the currency exchange section. Which is strange because for the most part, bitfinex appears to usually have greater volume then bitstamp (although both volume levels are very high).
I personally like to quote coinbase exchange rate because that is what I will use to exchange into and out of fiat. (This actually may be why bitstamp is more widely quoted then bitfinex because their verification process seems to be easier then bitfinex, making it easier to get fiat into and out of bitstamp).
But still, shouldn't we quote the biggest Usd exchange by the volume out there, regardless of the verification process? It might be rather that people are used to quoting Bitstamp as they were the biggest before their hack!
This was always weird to me. Everyone is quoting Bitstamp but Bitfinex is bigger than them. I have Bitfinex price on my Bitcoin widget. I don't know, it just makes sense following the biggest.