I've traveled to Japan, South Korea, Taiwan, and Hong Kong, and I'd say the quality of girls was great (really pretty ones) That said, the experience would have been even better if I had known the local language. It really does make a difference.
Luckily, in some places, I made local friends who helped me navigate/get references to the right agencies/madam. I also got lucky with a few girls (at a higher range) who claimed it was their first time with someone (though it's debatable whether they were actually virgins) I still had a really good time.
As for Amsterdam, prices can keep climbing because every service is an add on to the base rate. So depending on what you're looking for, you might end up paying a lot more than expected.
FKK scene in Berlin was an amazing experience too