Top 5 in Orchard Towers has the hottest Russian girls. Many aren't prostitutes though, but the hottest girls on the planet. They want you to drink with them - they get a commission on what you spend.
The hottest prostitutes are in Brix (Grand Hyatt) - if you get there early (10.30ish) the ratio is about 4 girls to 1 guy and without a lie, 80% are glamours. Going rate is $400 for 2 hours and $600 overnight. But trust me, these are gorgeous girls.