I would agree that Orchard Towers is not great but that said I have had some good experiences there, last year found a young girl, claimed to be a student, for SGD 300 for an overnight. Did however spend some money on crappy beer before that.
Otherwise I have found the Sammyboy forums helpful and I have had several good punts with Thai girls. Not as cheap as in Thailand but often SGD120-150 for 90 minutes (usually 2 shots, bbbj, cim, dfk). Often easy to book via whatsapp. Pictures are often photoshopped but have still felt that it has been reasonably accurate.
Sammyboy is a good source for Thai FL (Dome 1) and Chinese girls (FL Dome 2) who work from hotels.
For a Thai SGD100-150 (GBP 55-90) with hotel and protection included for usually 2 shots. Most speak at least a few words of English, some speak basic English.
Chinese are similar prices but are less accessible to westerners and more variable on price/services. They often don't speak English and may not accept westerners.
In FL Dome 3 there are smaller numbers of girls from Indonesia and other SE Asia countries (Vietnam, Philippines) and Korea (more expensive). There are also girls from many other countries world wide but at "international" price levels rather than local prices.
In FL Dome L they claim they are local girls (Chinese and Malay ethnicity) - prices are higher.
There are also sections with Field Reports on Geylang and Petain and Desker/Rowell Roads, the red light areas authorised by the government and legal.
Geylang is mostly Thai and Chinese girls with a few others. Geylang operates a system where punters can go into the houses and see the girls before choosing - they sit in a room where they can be seen. Geylang is a legalised brothel area and the houses are safe and the girls have health checks and working visas. The red light district occupies the even-numbered streets (called Lorongs), with most of the brothels located along Lorong 24, 26, 28, and 30. In that area and around Geylang there are also a lot of FLs working on the streets and using the short time local hotels. Not legal, no health checks, a bit less safe, by Singapore standards.
Petain women are older and prices lower and they work in their own rooms in houses which punters can walk around but they will not encourage tourists.
Desker Road and Rowell Road in Little India caters more for Indian workers, lower prices, simpler facilities and is also an area used by transgenders who are not legal.