Finex has...
Higher volume
1/2 price fees
Margin trading
Better liquidity
Bitfinex = 646, China= 646.... Stamp = 625....
So.. the question is... why keep bitstamp up the top when its over priced, lacking features, crap site, crap liquidity and price is also gox like at odds with china and other exchanges.
The volume thing may be a temporary situation. They are pretty much neck-on-neck at the moment regarding volume and Bitstamp could easily fall back to #1. Also, stamp has no margin trading, so without margin bitfinex would be many times smaller in volume.
I give you that on the fees and functionality. However, Bitstamp is designed with new users to cryptocurrencies in mind (i.e. very basic). Bitfinex has a higher proportion of pure speculators than Bitstamp and hence its price does not reflect the non-speculative demand for bitcoin as much as on Bitstamp.