I guess NYC because of so many potential clients.
yes, it was the golden era and those who worked then and saved/invested the money made a fortune. Less competitors and no alternative ways of hiring guys. Besides there was craigslist and backpage for low income/PNP clients and that kept them away from bothering escorts in mainstream sites like men4rentnow.com and rentboy.
one more thing @Merboy the best city for one guy could the worst for another one. Many things depend on demand and looks, getting lucky catching a big spender in a town also makes a big difference.