The lootsystem of the game isn't an open 1 to 1 system (meaning nobody who doesn't work for anet really understand how it works). however there is also no right asnwer to your question. Gold drops are subject to loot scaling. Making the party size as well as the kill speed a factor. But both things aren't something you should mind bout. it is not so big that if you kill boss Y faster he has a notable higher drop rate.
So no there is no boss or area you can go to to get better drops. The only thing you can do to really increase the drop of golds is by turning on hard mode.
For the rest, a lot of people have claimed to understand the system, but nobody I've met so far could proof it.