Grizzleheim - Vestriland - Halfang's Cave is where most people farm for gold. He drops expensive items that sell for a lot in the Bazaar. It adds up rather quickly and there's usually other people farming you can join.
Comparing Grizzleheim to Wysteria, probably Wysteria, but comparing Wysteria to Wintertusk (you reach it once you've completed Grizzleheim) Wintertusk has waaaaaaay more gold than any other place.