I have actually done both and this is a very good question. It depends on many things and what do you like ? I have been to brazil and Thailand. When I was in Brazil ( Rio de janeiro) the prices can be very expensive if you go to the whore clubs, you pay an entrance fee, you pay for the room , there are cheaper ones but you have to have a local with you and cant find it yourself. you can find street whores in rio but they triple the price if they know you a foreigner most of the time. The cheaper places are in rougher areas and again you need a local to take you there. However, some of them have great bodies over there. So it depends if that's worth the Hussle for you
Thailand will be lighter on your wallet than south America and I am not talking just talking about hookers, I am talking overall but its starting to get more expensive now. It will be a lot safer but it also depends on what your taste is ?